Switchcraft Stereo Headphone Jack- 3 Circuit Conductor with Nut and Washer, Double Open Circuit. Contact springs are of special alloys for long life. Insulation is high dielectric strength phenolic.  Tinned terminal lugs for easy soldering. Short frame.  Mounts by 3/8-32 threaded bushing and nut.  Open circuit until plug inserted.

SWC-12B