7 PIECE DEPTH STOP COLLARS BY PEACHTREE WOODWORKING PW915 7 piece set has collars to fit these drill bits; 1/8", 3/16", 1/4", 5/16", 3/8", 7/16", and 1/2" plus hex wrench Oxide steel stop collars use hex screws (wrench included) to tighten the collar around the bit