HRC 48-50 STEEL: Made of special steel with heat treatment, these drill bits have high hardness reaching HRC 48-50, elongated core and high concentricity for long-lasting use.6 SLOT DIAMETER: With 6 pieces per pack, These saw bits have different diameters of 1/4 inch (6.4 mm), 5/16 inch (8 mm), 3/8 inch (9.5 mm), 1/2 inch (12.7 mm), 9/16 inch (14 mm) and 5/8 inch (16 mm).MATCHED FOR DOUBLE EFFECT: They will achieve double effect by matched use with mortise and tenon machine, punching square holes should use drill electric, hammer and other tools.WIDELY APPLICABLE: They are great accessory for mortising, chisel and woodworking, suitable for construction, installation, renovation, decoration industry, etc. .SERVICE: We sincerely hope that you can get a good shopping experience in our store, if you have any questions, please feel free to contact us.Set of 6 Square Hole Drill Bits, Steel Hollow Chisel Carpentry Tools SetProfessional Drill Bit , suitable for construction, installation, renovation, decoration industry, etc.6 pieces per pack with different slot diameters to meet your needs.Slot diameter / weight1/4inch (6. 4mm) / 106g5/16inch (8mm) / 131g3/8inch (9.5mm) / 154g1/2inch (12.7mm) / 195g9/16inch (14mm) / 214g5/8inch (16mm) / 222gWeight about 1215g.