Compare the specs of the Roto Grip UFO Alert and Roto Grip Gem side by side in the ball comparison table below. To view the full bowling ball review for one of these balls, click the ball name link in the table below.
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| Brand | Roto Grip | Roto Grip |
| Ball Name | UFO Alert | Gem |
| Cover Name | eTrax Hybrid | MicroTrax Solid Reactive |
| Cover Type | Reactive Hybrid | Reactive Solid |
| Box Finish | 1500 Grit Polished | 2000 Abralon |
| Color | Purple Solid / Emerald / Teal | Citrine / Ruby / Amethyst |
| Core Name | E.T. (Equalizer Technology) | Defiant LRG |
| Core Type | Asymmetrical | Asymmetrical |
| RG | 2.52 | 2.47 |
| Total Diff. | 0.054 | 0.053 |
| Int. Diff. | 0.016 | 0.016 |
Torque Length Back End Total Hook Ball Tester Ratings | Already a premium member? Click here to log in. | |