A multifaceted reflector (MR) light bulb is a format for halogen bulbs, made by a variety of manufacturers. MR lamps were originally designed for use in slide projectors, but are now used in applications including residential lighting and retail lighting.
MR bulbs are one of the most widely used light bulbs. MR bulbs, or multi-faceted reflector bulbs, are used in a multitude of industries and applications including medical endoscopes, a DJ’s lighting rig, and overhead projectors. Odds are you have seen MR bulbs before, but don't realize it.
The number in the MR bulbs title correlates to the length of the bulb’s diameter, each digit equals one-eighth of an inch. For example, the MR11 bulbs are 11/8 inch in diameter, or 1 3/8 inches; likewise, a MR8 bulb is 8/8 inch in diameter, or 1 inch. MR bulbs come in many different sizes from the very common MR16 bulbs, to the somewhat common MR8 bulbs and MR11 bulbs, to the less widely known MR13 bulbs and MR18 bulbs.
MR bulbs also come in a variety of colors, these MR colored bulbs are commonly seen in DJ lighting rigs and concert lighting. MR colored bulbs are also used during a variety of events such as haunted houses at Halloween and Fall festival plays at schools.