Fits all mortising machines and drill press attachments 4 - 1/4-Inch, 5/16-Inch, 3/8-Inch and 1/2-Inch Made of the highest quality tool bearing steel High performance flute design geometry for superior chip extraction Hardness: HRC 48~50 Features: Professional wood drill bit, suitable for construction, installation, renovation, decoration industry, etc. Special steel, heat treatment, HRC48~50, high hardness, lengthened core, high concentricity. It will get double effect by matched use with mortise and tenon machine, the square hole punching needs to use electric drill, hammer & other tools. Specifications: Hardness: HRC 48~50 Holder diameter: 19mm (circular) Drilling core length: 195mm Slotting flute diameter Total weight 001 1/4 inch(6.4mm) 150g 002 5/16 inch (8mm) 161g 003 3/8 inch (9.5mm) 177g 004 1/2 inch (12.7mm) 206g Shaft length: 1/4 inch(6.35mm): 60mm 5/16 inch(8mm):60mm 3/8 inch(9.5mm):75mm 1/2 inch (12.7mm):60mm Color: silver + black Material: bearing steel Package Contents: 2pcs Opening tool