Features 1、The set includes drill bits for drilling pilot holes, screw sizes are 3mm, 4mm, 5mm, 6mm, 7mm, 8mm, 10mm. 2、Specially designed steel countersunk or countersink guide holes. 3、Drilling and countersinking wood screws without changing drill bits. 4、Just loosen and tighten the set screws to adjust the drilling length of screws of various lengths. 5、5 flute design for quicker wood chip removal during use. 6、Smooth and flat countersunk, and the nut is perfectly embedded in the surface of the workpiece. Specification Item Type: Countersunk Drill Bit Dimension: 3mm x 60mm(L) Chamfer Diameter: 15.8mm 4mm x 75mm(L) Chamfer Diameter: 15.8mm 5mm x 85mm(L) Chamfer Diameter: 15.8mm 6mm x 93mm(L) Chamfer Diameter: 15.8mm 7mm x 100mm(L) Chamfer Diameter: 15.8mm 8mm x 110mm(L) Chamfer Diameter: 18.8mm 10mm x 120mm(L) Chamfer Diameter: 18.8mm Shank: 1/4 hex shank Size Error: ±2mm Package List 7 x Countersunk Drill Bit 1 x Hex Wrench