20 PCS METRIC & SAE: 4’’ long hex drill bit set, Include 10pcs SAE hex bits set -5/64”,3/32”, 7/64”, 1/8”, 9/64”, 5/32”, 3/16”, 7/32”, 1/4”, 5/16”. 10pcs metric hex bit set-1.5mm, 2mm, 2.5mm, 3mm, 3.5mm, 4mm, 5mm, 6mm, 7mm, 8mm CNC/S2 GRADE MATERIAL: This allen bit set is made of S2 alloy steel body, CNC machined tips and hardened core, enhancing bit strength and minimize the risk of breakage. The surface is treated with manganese Phosphate to prevent rust TORSION ZONE DESIGN: This hex head drill bit set is designed with torsion zone to fully absorb torque peaks to avoid breakage. 1/4" Hex-Shank is compatible with most impact driver and heavy screw driving Elongated for Wider Applications: This hex head allen wrench drill bit set is extended to 4 inch length, a 2.3 inch extension socket also included for wider application. Helping you tackle with more complex working angles and depths and improve efficiency Widely used in home repairs, automobiles, woodworking and other screw driving applications. All day after-sale service.Any problems about BRETREEAD impact hex bit set, please contact us for service Impact Hex Head Allen Wrench Drill Bit Set 20pcs (Metric&SAE), 1/4" Impact Hex Shank S2 Steel Hex Bit Set, Allen Key Drill Screwdriver Bit Set With Magnetism&2” Long With Storage Box.