The 800-0331-500 is a sub-miniature incandescent press-to-test indicator designed for back-of-panel mounting in a 15/32" clearance hole, featuring a red transparent lens and non-dimming mechanical shutter semi-blackout design. It meets or exceeds the requirements of MIL-L-7961B and MIL-L-3661 military standards and is designed for use with 3-terminal assemblies. The indicator uses a T-1¼ bulb with midget flange base and features a 5/16-32 NEF threaded lens holder constructed from aluminum with black anodize finish, brass hot-tinned terminals with elongated slots, and phosphor bronze internal-tooth lockwashers with white nickel finish. The maximum panel thickness is 5/16" with a maximum projection of 7/8" back of panel. This indicator is commonly used in remote control applications and circuit monitoring where a reliable visual status indication is required in compact panel-mounted configurations.