Cordless magnetic drill presses rotate annular cutters or other bits to make holes in structural steel, I-beams, pipe, and other metal workpieces. Also known as mag drills, their magnetic base sticks to ferrous metal surfaces and holds the drill in position as the cutting bit is fed into the material. They operate in a vertical, horizontal, or upside-down position and require tethering with a strap or chain to prevent them from falling or sliding if the base loses magnetic hold. These portable drill presses are used in steel fabrication, construction, bridge building, and other applications on materials that are fixed in place or too large to bring to a stationary drill press. Cordless mag drills operate in areas without access to wired power and run on brand-specific batteries, which fit different tools from the same manufacturer. Battery voltage and series must be compatible with the tool.