Vise Grip P/O Bowling InsertOne side of the insert is an Oval cut and the other side is a Power LiftDrill Size 31/32″: 9/16, 37/64, 19/32, 39/64, 5/8, 41/64, 21/32, 43/64, 11/16, 45/64, 23/32, 47/64, 3/4, 49/64,25/32, 51/64 and 13/16.Drill Size 1-1/32″: 53/64, 27/32, 55/64, 7/8, 57/64 and 29/32.The Power Lift helps the bowler create more revs with the 1/4″ forward pitch that aids grip. The oval side provides the perfect natural feel for a smooth consistent release.Vise P/O Inserts are available in 32 sizes and 12 colors.