The 3pcs screwdriver extension bits are built have magnetic, for use in hand held drivers or power drills, to extend all kinds of screwdriver bits. Features: Interface has a locking mechanism, built have magnetic, automatically pop up batch head. Extend all kinds of screwdriver bits, screwdriver head conversion uses. Fast fastening, greatly improve work efficiency. For use in hand held drivers or power drills, this 1/4 inch female by 1/4 inch male magnetic bit holder. Helpful to remove or tighten a large number of screws after you've started or loosened them. Suitable for drill, screwdriver, batch head and other to transfer. Has a hardened and tempered steel shaft with a quick release chuck. Specifications: Material: Chrome Vanadium Steel Color: Black Hex Shank: 6.35mm( 1/4" ) Fir for: 1/4" shank dirver bit Package Weight: 118g / 4.16ounces Package Size: 170 * 50 * 10mm / 6.69 * 1.97 * 0.39in Packing List: 3 * Screwdriver Extension Bits