This set incorporates two drill countersinks and matching plug cutters. Plugs cutters are made from Tool Steel and are very slightly tapered. Use on timber to drill a countersunk hole for a screw which is then plugged uses a plug/pellet made using the plug cutter. Recommended that plug cutters are used in a pillar drill. Specifications • Shank Diameter: 1/4 hex • Type or Grade: For No.8 & 10 • Pack Qty: 4 piece Contents: 1 x Drill/countersink for No. 8 x 9.5mm 1 x Drill/Countersink for No. 10 x 12.7mm 1 x Plug cutter 9.5mm (3/8 inch) 1 x Plug cutter 12.7mm (1/2 inch) Contents • No.8 drill/countersink • No.10 drill/countersink • Plug cutters (x2) • Hexagon key