Parallel ground tips to better fit the bottom of the slot, where the screw is strongest, for greater torque transfer. Fit a wide selection of factory screws. #6 X-L has a 12" long shank for buttstock screws/bolts. Because of the end use of this product, Forster offers a warranty on manufacturing defects but not misuse/abuse. Mfg: Forster SPECS: Tip sizes from 1⁄8" (3.1mm) to 11⁄64" (4.3mm) wide, .023" (.58mm) to .035" (.88mm) thick. Set of 8 in soft plastic case. #6 X-L has a 12" long shank.