Featuring NEW Clam Shell package for better display and easier fitting. Unlike traditional finger inserts used in 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 axis rotation for more hooking reaction. 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 discomfort caused by excessive friction during release. Turbo Rev is available in four sizes: S, M, L, XL. Size Equivalent: Small = 19/32 - 5/8, Medium = 21/32 - 11/16, Large = 23/32 - 3/4, XL = 25/32 - 13/16 Assorted Colors