These bulbs are sized to fit older telephone switchboards, signs, instruments, and indicators. Brightness is measured in lumens; the higher the lumens, the brighter the bulb.

LED bulbs last longer and are more efficient than other technologies. They generate little heat and withstand vibration.

Incandescent bulbs are traditional light bulbs.

Bulbs for General Electric ET-5 and ET-6 sockets must match the ohms listed on the back of your socket.