The Switchcraft 3-Conductor 1/4" Long-Frame Telephone Twin Jack has both the tip and ring circuits interconnected (crossover wired), so if a plug is inserted in either jack, common circuits are opened. It is used in Switchcraft Series 2400, 2600, and JP Jack Panels and other standard jack panels. The jack's solder lugs are equivalent to WEco 482A and the jack is adjusted for WEco type 310 (MIL types M642/2-1 and M642/2-2) plugs.
Mounting screws (#6-32) are not included.
Switchcraft MT389 Specs
Frame and Stack Screws: Steel, plated with iridescent iridite finish
Copper alloy, spring tempered Solder lugs are solder coated
Nickel-plated copper alloy
Welded crossbar palladium in shunt circuits
Rigid plastic (MIL-type PBE-P, per MIL Specification LP-513C) Extruded plastic insulating tubing through stack
10-MOhm maximum (initial), 20-MOhm maximum (after life), 100-MOhm maximum (after salt spray)