A multifaceted reflector (often abbreviated MR) light bulb is a reflector housing format for halogen as well as some LED and fluorescent lamps. MR lamps were originally designed for use in slide projectors, but she used them in residential lighting and retail lighting as well. They are suited to applications that require directional lightings such as track lighting, recessed ceiling lights, desk lamps, pendant fixtures, landscape lighting, retail display lighting, and bicycle headlights. MR lamps are designated by symbols such as MR16 where the diameter is represented by numerals indicating units of eighths of an inch. Common sizes for general lighting are MR16 (16⁄8 inches, 51 mm) and MR11 (11⁄8 inches, 35 mm), with MR20 (20⁄8 inches, 64 mm) and MR8 (8⁄8 inch, 25 mm) used in specialty applications. Many run on lower voltage rather than mains voltage alternating current so requiring a power supply.