 A tiny E5 or E5.5 size is used only for extra-low voltages, such as in interior illumination for model buildings, and model vehicles such as model trains.These are often called "pea bulbs" if they are globe-shaped, but they commonly look like mini Christmas bulbs, or large "grain-of-wheat" bulbs.E10 bulbs are common on battery-powered flashlights, as are bayonet mounts (although those are usually held in with a circular flange located where the base meets the glass envelope of the bulb).