In-tool-home Woodworking 1/4" Hex Shank Replacement Twist Step Drill Bit for Manual Pocket Hole Guide Jig Master System Made specifically for Pocket-Screw Joinery. 1/4" hex shank works with any quick change chuck. drill guide for pocket holes.work well with the Manual Pocket Hole Jig Master System, or alone Drill bit tools for use with pocket hole joinery and perfect replacement The diameter:3/8"(9.5mm),the shank is 1/4" hex