2-Conductor phono jack for rear-of-panel mount, using 3/8-32 locknut (supplied). Locknut can be tightened conveniently by holding .438 in (11.12 mm) hex body with Spintite wrench from rear. Can be mounted on .688 inch (17.48 mm) centers through .391 inch (9.93 mm) diameter hole in panels up to .203 inch (5.16 mm) thick.