HTS 100B1 Magnetic Adjustable Depth Bit Holder Eliminate guess work setting screws straight and to a predetermined depth Spring loaded ball bearings to securely hold sockets Strong, internally mounted magnet for simple 1/4" hex bit changes Hardened shaft and nickel plated body resists corrosion and provides exceptional durability Designed for use by drywall professionals, it is also good for wood framing, deck building, installation of plywood subfloor, crate building, and more