Jacks are standard 1/4" phone jacks with extra long threaded bushing for mounting in panels/chassis up to 1.25" thick. Metal bushing virtually eliminates hum pick-up, and is ideal for electric guitar and speaker connections. Jacks mate with standard commercial 1/4" phone plugs. Jacks mount in a single .469" diameter hole. Rugged cable clamp protects connections from twisting and pulling stresses.