Mono RCA jack, 3.20 mm ID, panel mount
The 598 is a female mono RCA phono jack from Keystone Electronics, carrying 2 conductors and 2 contacts with a 3.20 mm ID / 9.00 mm OD industry-recognized mating diameter. The nickel-plated brass body and contacts suit standard line-level audio signal paths; the unshielded shell leaves ground-loop management to the system chassis.
Panel hole and thread fit
Mounts through a 0.375" (9.52 mm) panel hole and secures with a 1/4"-32 threaded nut — the included mounting hardware and grounding tab complete the installation without additional fasteners. Termination is via solder eyelet(s), which accept the centre conductor and shield braid of a standard RCA cable; the internal switch is absent, so the jack passes signal continuously.