Pins on either side of the base lock these bulbs into sockets. Pins are directly across from each other.

Offset pins on the base lock these bulbs into sockets. One pin is slightly higher on the base than the other pin.

These miniature bulbs are sized to fit older telephone switchboards, signs, instruments, and indicators.

These bulbs are sized to fit tight spaces such as signs, control panels, indicators, and flashlights.