The MP7905 Magnetic Pickup (3/4" x 4 1/2" long) has a total length of 4 1/2 inches, threaded length of 4 1/2 inches, and thread size of 3/4-16 UNF. It replaces 20-01-0082. The leadwire hookup measures 12 inches (305 mm).
Magnetic Pickups supply RPM data to a tachometer when mounted at the flywheel ring-gear of an engine.