50 WATT AR18 TYPE GBK HALOGEN LIGHT BULB - D.C. BAYONET BASE - 25 DEGREE BEAM SPREAD NARROW FLOOD - LONG LIFE 4,000 HOURS ALUMINIZED REFLECTOR BULB -  This MR11 aluminized reflector lamp has a frosted front glass for use in vanities, audio-visual, photographic, projector, and stage lighting applications. Supra Life AR18 halogen lamps use a quartz envelope for durability and pure tungsten for longer life. The regeneration cycle continuously restores the filament, creating a 6 times longer burning life. Precision reflectors provide excellent light control with a fluted mirror.