A comfortable and properly fitted grip is essential to a good release. One (1)insert included in price. Image shows difference in the 2 sides of insert.Style Combo: Semi Finger Tip and Power NubSemi Finger Tip, or Bump Grip (as it is frequently referred.)The Semi finger tip insert has a smooth, rounded bump close to the front edge of the insert. When properly fit, the bump rests between the first knuckle of the finger. It is designed for a more relaxed grip and ideal for bowlers who suffer from arthritis or have weak grip pressure.Power NubThe finger pad of the Power Nub is lined with rows of small, raised bumps. The Power Nub has a very sharp feel and is not for the faint of grip! This style is recommend for a strong grip.Quad finger inserts have the standard 31/32 outer diameter in sizes 19/32-13/16 and a 1-1/32 outer diameter in larger sizes. As an added plus, each Quad insert is designed with a patented Glue Groove to minimize excessive adhesive from seeping to the surface of the ball during installation. For Turbo Grips, if the outside of your insert says:19 choose 01-19/3239 choose 015-39/645 choose 02-5/8 41 choose 025-41/6421 choose 03-21/32 43 choose 035-43/64 11 choose 04-11/16 45 choose 045-45/6423 choose 05-23/32 47 choose 055-47/64 3 choose 06-3/4 49 choose 065-49/64 25 choose 07-25/32 51 choose 075-51/6413 choose 08-13/16 53 choose 085-53/64 27 choose 09-27/32 7 choose 10-7/8 29 choose 11-29/32For Vise Inserts, if the outside of your insert says:1 choose 01-19/321 1/2 choose 015-39/642 choose 02-5/8 2 1/2 choose 025-41/643 choose 03-21/32 3 1/2 choose 035-43/64 4 choose 04-11/16 4 1/2 choose 045-45/645 choose 05-23/32 5 1/2 choose 055-47/64 6 choose 06-3/4 6 1/2 choose 065-49/64 7 choose 07-25/32 7 1/2 choose 075-51/648 choose 08-13/16 8 1/2 choose 085-53/64 9 choose 09-27/32 10 choose 10-7/8 11 choose 11-29/32Product Type: Bowling Accessories