This drill bit set is intended for the installation of detachable or non-detachable swivel bases. The set comes with a drill for 3/4" and 1/2" woodscrew and a second drill for 7/8" machine screw. The bits are made of high carbon stress proof steel and provide clean cutting on laminate, synthetic or wood stocks. Prevents swivel from touching firearm when sling is properly connected. Quick release feature for easy mounting or removal.