Rta furniture step drill bit creates steps for the confirm at style furniture screw. Used for drilling pilot hole, clearance hole and Countersinking, #55290, (B) Cutting height: 15mm, (D) diameter: 3.5mm, (D) shank: 1/4, overall length (L): 60mm, B1: 5mm, D1: 5mm, D2: 7mm, D3: (7mm), L1: 33mm, 55290 RTA furniture drill/Countersink with Quick release 1/4 hex shank for 5mm screw