Turbo 2 N 1 Grips Bowling Accessories. Unlike traditional finger inserts fit into a bowling ball, Turbo Rev is designed to be worn on the index or pinkie finger. When worn on the index finger, Turbo Rev will help create more axis rotation for more hooking action. When worn on the pinkie finger, Turbo Rev will help reduce axis rotation giving you a more even and controlled ball reaction. But most importantly, Turbo Rev is designed to protect your fingers from unsightly and painful calluses caused by excessive friction during release.Random colors will be shipped.