The Mag Daddy – Magnetic Clamp is ideal for strapping wire to metal areas. Featuring an easy open/close 1/2" diameter clamp and rated 15 lbs rare earth magnet. Locations they can be used: Steel, Beams, Purlins, Ceiling Decks, Drop Ceiling Channels, Metal Joists, Frame Rail, Screw Heads, Metal Washer, etc.