SWITCHCRAFT 1/4' STEREO JACK
JACK, 1/4", TIP-RING-SLEEVE, OPEN CIRCUIT, WIRED, Switchcraft®
Used with T/R/S plugs for either balanced connections or stereo connections.
Also very common in guitars with active pickups, and as the input jack on some effects pedals.
The ring conductor is used in these cases to "turn on" the battery by tying one leg of the battery to ground via the plug.

