THE WEIGHTBLOCK

A Bowling Balls Engine

Toggle between Asymmetric and Symmetric weightblock cores

ASYMMETRIC

SYMMETRIC

CORE FUNDAMENTALS

The weightblock is the engine inside your ball.
It shapes how energy is stored and released.

Symmetrical vs Asymmetrical

“Predictable arc vs directional kick.”

Sym = smoother, more predictable shape
Asym = sharper, faster-responding motion

EXPLORE

Symmetrical vs Asymmetrical Cores

Predictable Arc vs Directional Kick

Symmetrical and asymmetrical cores share the same goal — to create motion on the lane — but how they generate that motion is what sets them apart.

Symmetrical Core

A symmetrical core has evenly distributed mass, producing a smoother and more predictable motion.

RG: 2.48

Diff: 0.051

Psa: n/a

Asymmetrical Core

An asymmetrical core includes a defined Preferred Spin Axis (PSA), allowing it to change direction faster once it finds friction.

RG: 2.48

Diff: 0.050

Psa: 0.020

Benefits of Symmetrical vs Asymmetrical weightblocks

Symmetrical Core

More predictable, benchmark motion that’s easy to read.
Smoother recovery off friction — ideal for control and consistency.
Great for blending transition and maintaining forgiveness.
Best choice when you want a rounder, more readable shape.

Asymmetrical Core

Responds faster to friction — adds power and angle downlane.
More dynamic motion with stronger continuation through the pins.
Allows greater layout versatility via the PSA.
Best choice when you need to open up the lane or maximize backend motion.

When to Use Each Core Type

SYMMETRICAL CORE When Control Matters Most

Fresh or early friction conditions: smooths out overreaction on dry or blended lanes.
Benchmark ball testing: perfect for reading the lane before making big moves.
Lower rev or speed-dominant players: helps keep the ball controllable and predictable.
Transition games: when asym balls start jumping too hard, a symmetrical blends the shape.
Goal: maintain control, repeatability, and smooth motion through transitions.

“Think of a symmetrical as your truth teller — it shows you what the lane is really doing.”

Asymmetrical Core When You Need Extra Motion

Heavier oil or longer patterns: helps the ball dig in and create angle when symmetrics can’t.
Higher rev or matched players: enhances responsiveness without needing to force it.
When you want to open your angles: adds backend torque for a stronger entry angle.
Later games or higher friction with speed players: keeps energy and drive through the pins.
Goal: maximize power, angle, and versatility through tuning the PSA and layout.

“Asymmetricals give you a toolbox — the power to shape motion beyond surface alone.”

ARSENAL SYNERGY How Both Fit Into Your Bag

SYMMETRICAL

Establishes a controllable foundation. Smooths transitions, improves friction read, and delivers consistent reaction.

ASYMMETRICAL

Adds power on top of control. Responds faster to friction and creates more shape when you need to open angles.

Used together, they form a complete toolkit.

RG (Radius of Gyration)

“How fast the ball revs up.”

Low RG = starts earlier.
High RG = saves energy, pushes longer.

EXPLORE

RG: When the Ball Starts to Rev

Low RG revs up earlier. High RG saves energy and revs later down the lane.

LOW RG

HIGH RG

LOW RG VS HIGH RG: HOW THEY REACT

Two bowling balls can share a similar differential, yet react completely different depending on their Radius of Gyration (RG). RG influences how quickly the ball revs up and transitions through the lane.

Low RG + Similar Diff

RG: 2.48

Diff: 0.043

Rev-up starts earlier in the midlane.
Creates stronger traction and earlier motion.
Best choice when you need earlier read and control in heavier oil.

High RG + Similar Diff

RG: 2.55

Diff: 0.045

Stores more energy through the front part of the lane.
Delays rev-up for sharper backend motion.
Ideal when you want clean fronts and strong backend reaction.

BENEFITS OF LOW RG AND HIGH RG

and why you need them in your arsenal

Low RG

Revs up faster and transitions earlier on the lane
Creates smoother, more stable motion in the midlane
Helps blend wet/dry conditions
Ideal when you need the ball to read the lane sooner

High RG

Stores energy longer before transitioning
Creates more length through the front part of the lane
Produces stronger motion downlane when paired correctly
Useful when you need the ball to clear the heads cleanly

Differential

“How much potential the ball has to change direction.”

High Differential = greater change of direction (bigger move).
Low Differential = less change of direction (smoother, straighter).

EXPLORE

Differential: Change of Direction

Low Diff = smoother, less change of direction.

High Diff = bigger move, greater change of direction.

HIGH DIFF

LOW DIFF

From Specs to Lane Reality

On paper, the numbers don’t look far apart — 0.029 vs 0.053. But on the lanes, it’s the difference between a smooth, benchmark arc and a sharper, more aggressive move.

LOW DIFF + SIMILAR RG

RG: 2.49

Diff: 0.029

Lower differential = smoother, more controllable motion.

HIGH DIFF + SIMILAR RG

RG: 2.47

Diff: 0.053

Higher differential = stronger change of direction.

BENEFITS OF LOW DIFF AND HIGH DIFF

and why you need them in your arsenal

Low Differential

More predictable motion, easier to control
Handles transition and breakdown smoothly
Great benchmark reaction to read the lane
Reduces risk of over-reaction when friction is high

High Differential

Maintains hook potential in heavier oil.
Gives the ball the ability to change direction when oil is present
Supports stronger overall motion

Intermediate Differential (PSA)

“How fast it changes direction.”

Higher int. diff = sharper/more defined move.
Lower int. diff = transition is slower and smoother.

EXPLORE

PSA – How Fast Asymmetrical Cores Transition

Differential shows how much total direction change a ball can make.
Intermediate Differential (PSA) shows how fast that direction change happens once it starts.

HIGH PSA

LOW PSA

INTERMEDIATE DIFF IN ACTION

See how two bowling balls with similar Rg and Differntial react with differnt intermediate ratings.

High Intermediate

RG: 2.51

Diff: 0.051

Int: 0.016

High Int. Diff: transition curve is steeper, compresses into a quick change.

Low Intermediate

RG: 2.50

Diff: 0.056

Int: 0.008

Low Int. Diff: transition curve is stretched out, arcs smoothly before finishing.

BENEFITS OF LOW PSA AND HIGH PSA

and why you need them in your arsenal

Higher Intermediate Diff (strong PSA):

Once friction is encountered, the core transitions faster
Motion becomes sharper and more angular
The breakpoint looks quick and defined
Often creates a “flip” look rather than a smooth arc

Lower Intermediate Diff (weaker PSA):

Once friction is encountered, the core transitions slower
Motion blends out and looks smoother
The breakpoint appears rounder
Can resemble the motion of a symmetrical ball

HOW RG & DIFFERENTIAL COMBOS COMPARE

See how common RG/Differential combinations translate to ball motion and lane use. Filter by brand to focus on Storm, Roto Grip, or 900 Global.

RG + DIFFERENTIAL	REACTION INTENSITY	IDEAL LANE ENVIRONMENT	REACTION PROFILE
Low RG + Low Diff	Early – Smooth	Short patterns, control-focused play	Stable shapes that blend the lane
Low RG + Mid/High Diff	Early – Round / Arc	Heavy oil, fresh patterns	Strong midlane read with defined motion
Mid RG + Low/Mid Diff	Midlane – Round	Medium patterns, benchmark control	Versatile, readable motion
Mid RG + High Diff	Midlane – Arc / Angular	Transition phases	Stronger direction change off friction
High RG + Low/Mid Diff	Late – Arc	Dry lanes, longer patterns breaking down	Clean fronts with controlled backend
High RG + High Diff	Late – Skid Flip	When entry angle is needed	Maximum length with sharp backend motion

HOW TO CHOOSE A CORE FOR YOUR GAME

Match core dynamics to your rev rate and preferred motion shape.

Speed Dominant

Lower RG cores
Higher differential designs
Stronger midlane read

When ball speed exceeds rev rate, lower RG cores help the ball transition sooner, creating earlier rotation and stronger continuation through the pins.

Rev Dominant

Higher RG cores
Lower or mid differential
Controlled backend motion

Higher rev players typically benefit from higher RG cores that delay transition, preventing early roll-out and preserving energy for a smoother backend move.

Balanced

Mid RG cores
Mid differential
Benchmark-style shapes

Balanced players often prefer mid RG, mid differential cores that provide predictable motion and versatility across a wide range of lane conditions.

SPI CORE LINEUP

Every core across Storm, Roto Grip, and 900 Global is engineered for a specific motion profile. Explore how each family differs in shape, energy retention, and best use cases.

Element™ Max A.I. Core

Asymmetric

Low RG asymmetric design that revs quickly and creates strong, defined midlane motion with increased flare potential and torque.

Used In Ion Max Ion Max Pearl

Torsion™ A.I. Core

Symmetric

Low RG symmetric evolution of the Element Max, delivering smooth stability in the midlane with a controlled, continuous arc.

Used In Bionic

Equalizer™ A.I. Core

Symmetric

Higher RG symmetric design engineered for delayed friction response and exceptionally smooth, repeatable transitions.

Used In Level

Radius weight block by Storm Bowling Products

Radius™ Core

Symmetric

Consistent, controlled symmetric shape engineered for smooth arc motion and dependable traction across all weights.

Used In Concept

Velocity Core

Symmetric

Fast-revving symmetric core with higher differential, offering smooth backend motion without sharp overreaction.

Used In Phaze II Phaze II Pearl

C3 A.I. Core weight block by Storm Bowling Products

C³™ A.I. Core

Symmetric

Forgiving, quick-revving symmetric design enhanced with A.I. technology for improved energy transfer and expanded strike window.

Used In IQ Tour A.I.

Inverted Fe2 Technology core weight block by Storm Bowling Products

Inverted Fe² Technology™

Symmetric

Classic Thunder Line symmetric core delivering reliable length and controlled continuation with proven consistency.

Used In Hy-Road Hy-Road 40

Capacitor™ Core

Symmetric

High RG, low differential symmetric design offering long, smooth motion and exceptional predictability.

Used In Pitch Black

C3 Centripetal Control Core weight block by Storm Bowling Products

C³™ – Centripetal Control Core

Symmetric

Workable, forgiving symmetric core that revs easily and produces a smooth, predictable change of direction.

Used In IQ Tour

Atmos™ A.I. Core

Symmetric

Balanced symmetric design that stores energy through the fronts and delivers controlled power with midlane stability.

Used In Typhoon

ID™ A.I. Core

Asymmetric

Versatile asymmetric core with lower intermediate differential, delivering strong continuation without over-rolling too early.

Used In Identity Identity B/C/P

RAD-TQ™ Core

Asymmetric

High RG, high differential asymmetric core that clears the fronts easily and stores energy for a powerful, angular backend move.

Used In Next Factor

Solarion™ Core

Asymmetric

Low RG asymmetric core featuring a multi-cylinder design for fast revving, strong torque, and classic skid-flip continuation.

Used In Equinox Equinox Solid

Element™ Core

Symmetric

Center-heavy symmetric design that lowers RG and increases layout responsiveness for controlled yet dynamic motion.

Used In Ion Pro Ion Pro Solid

Surge™ Core

Symmetric

Higher RG symmetric shape providing easy length and a dependable, controlled move off the spot.

Used In Tropical Surge

Morph-Wing™ Core

Asymmetric

Dynamic asymmetric design engineered for dramatic layout responsiveness, allowing significant flare and motion changes based on drilling position.

Used In Transformer

RST™ A.I. Core

Asymmetric

Higher RG asymmetric core delivering strong torque and energy retention for enhanced downlane continuation.

Used In RST Hyperdrive RST Hyperdrive Pearl

Rondure™ Tour-X Core

Asymmetric

Lower RG, lower differential asymmetric design built for enhanced control and stability with a smoother, more centered motion.

Used In Gremlin Tour-X

High RG high differential Rondure MaxD bowling ball core weight block by Roto Grip

Rondure™ MaxD Core

Asymmetric

High RG, high differential asymmetric core engineered for maximum length, flare potential, and powerful continuation.

Used In Gremlin

Rocker™ + A.I. Core

Symmetric

Higher RG symmetric core enhanced with A.I. technology for extended length and strong, sweeping backend motion.

Used In Rockstar Rockstar Amped

Wrecker™ + A.I. Core

Symmetric

Higher RG symmetric design offering increased length and stronger direction change compared to the Hustle core.

Used In Ultimate Wrecker

Hustle™ Core

Symmetric

Medium RG, medium differential symmetric core delivering balanced control and versatile overall motion.

Used In Ultimate Wrecker

Ellipse™ A.I. Core

Asymmetric

Asymmetric single-density design with balanced Y and Z axis mass distribution for consistent torque and aggressive backend continuation.

Used In Origin Ex

Blast™ A.I. Core

Symmetric

High differential symmetric core delivering strong midlane read while preserving energy for reliable backend continuation.

Used In Vengeance

Strobe™ A.I. Core

Asymmetric

Higher RG asymmetric core engineered for controlled midlane read with a strong, defined backend motion.

Used In Viking

Magna™ A.I. Core

Symmetric

Dual-hemisphere symmetric design built for continuous, stable motion and consistent performance on medium conditions.

Used In Cove Ember

WHY NUMBERS DONT TELL THE WHOLE STORY

Two balls. Similar specs. Totally differnt reactions. Why the coverstock matters most.

RST HYPERDRIVE

RG: 2.52

DIFF: 0.055

PSA: 0.017

MICROTRAX™ SOLID COVERSTOCK

Our grippiest and most aggressive solid coverstock material features our highest ratio of nanoparticles mixed throughout. This formulated mixture not only provides the best traction in higher volumes of oil, it also creates a consistent reaction time and time again thanks to the displacement and absorption of oil.

RST HYPERDRIVE PEARL

RG: 2.52

DIFF: 0.055

PSA: 0.017

U-R1™ PEARL REACTIVE

Our newest formulation of pearlized nano-free material provides plenty of push through the front of the lane from every angle while providing ULTRA response to friction down lane. Without a doubt, every style of bowler will benefit from having this type of forgiveness down lane.

Learn About The Coverstock

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THE WEIGHTBLOCK

A Bowling Balls Engine

Toggle between Asymmetric and Symmetric weightblock cores

CORE FUNDAMENTALS

The weightblock is the engine inside your ball. It shapes how energy is stored and released.

Symmetrical vs Asymmetrical

“Predictable arc vs directional kick.”

Symmetrical vs Asymmetrical Cores

Predictable Arc vs Directional Kick

Symmetrical Core

Asymmetrical Core

Benefits of Symmetrical vs Asymmetrical weightblocks

Symmetrical Core

Asymmetrical Core

When to Use Each Core Type

SYMMETRICAL CORE When Control Matters Most

Asymmetrical Core When You Need Extra Motion

ARSENAL SYNERGY How Both Fit Into Your Bag

SYMMETRICAL

ASYMMETRICAL

RG (Radius of Gyration)

“How fast the ball revs up.”

RG: When the Ball Starts to Rev

LOW RG VS HIGH RG: HOW THEY REACT

Low RG + Similar Diff

High RG + Similar Diff

BENEFITS OF LOW RG AND HIGH RG

and why you need them in your arsenal

Low RG

High RG

Differential

“How much potential the ball has to change direction.”

Differential: Change of Direction

From Specs to Lane Reality

LOW DIFF + SIMILAR RG

HIGH DIFF + SIMILAR RG

BENEFITS OF LOW DIFF AND HIGH DIFF

and why you need them in your arsenal

Low Differential

High Differential

Intermediate Differential (PSA)

“How fast it changes direction.”

PSA – How Fast Asymmetrical Cores Transition

INTERMEDIATE DIFF IN ACTION

High Intermediate

Low Intermediate

BENEFITS OF LOW PSA AND HIGH PSA

and why you need them in your arsenal

Higher Intermediate Diff (strong PSA):

Lower Intermediate Diff (weaker PSA):

HOW RG & DIFFERENTIAL COMBOS COMPARE

HOW TO CHOOSE A CORE FOR YOUR GAME

Speed Dominant

Rev Dominant

Balanced

SPI CORE LINEUP

Element™ Max A.I. Core

Torsion™ A.I. Core

Equalizer™ A.I. Core

Radius™ Core

Velocity Core

C³™ A.I. Core

Inverted Fe² Technology™

Capacitor™ Core

C³™ – Centripetal Control Core

Atmos™ A.I. Core

ID™ A.I. Core

RAD-TQ™ Core

Solarion™ Core

Element™ Core

Surge™ Core

Morph-Wing™ Core

RST™ A.I. Core

Rondure™ Tour-X Core

Rondure™ MaxD Core

Rocker™ + A.I. Core

Wrecker™ + A.I. Core

The weightblock is the engine inside your ball.
It shapes how energy is stored and released.