Sealed beam lamps incorporate a parabolic reflector, filament, and a glass or polycarbonate lens sealed as a unit. Due to their reflector, sealed beam bulbs are also referred to as PAR lamps. These bulbs were used as automotive headlamps from 1939 until the model year 1984. Replacement sealed beam lamps are required for car enthusiasts and restoration experts that desire an authentic restoration of their antique and classic car headlamps. Sealed beam PAR64 bulbs have also been used in stage lighting in higher wattages with a variety of beam spreads. Colored gels are used over the PAR cans to change the color of the light emitted onto the stage. Like miniatures, the part numbers of sealed beam lamps are identified by a standard industry number that indicates physical and electrical characteristics. Lamp manufacturers that use the industry standard part number have designed their product to be in accordance to the American National (ANSI/NEMA) standards for sealed beam bulbs.