toolant impact hex head allen wrench drill bits. Torsion zone to absorb torque peaks to avoid breakage. For impact driver and heavy screw driving. 4mm*10pcs, 1/4” quick release hex-shank, 2” long. Nice choice for replacement bit. CNC machined tips, S2 alloy steel body, hardened core to increase bit strength and reduce fracture. Manganese Phosphate surface to prevent rust. Strengthened magnetic impact bit helps you easy pick up screws. The magnetism doesn’t decay after multiple uses. Widely used in home repairs, automobiles, and other screw driving applications. If you are not fully satisfied for any reason, please feel free to contact us via Amazon for 100% refund or replacement. Don’t forget to follow us on Amazon by clicking our brand name at the top of product page. :) toolant 4mm Impact Hex Head Allen Wrench Drill Bit Set 10pcs, 1/4” Hex-Shank S2 Steel Hex Bits Set, CNC Machined Tips with Magnetism, 2” Long with Storage Box