The HPL (High Performance Lamp) is a tungsten halogen single-ended lamp which is primarily used in the ETC Source Four Fixtures (aka S4, Source 4, Source Four Jr, Source Four PAR, Source Four PARNel, Source Four Fresnel). At 575 watts, the HPL lamp in a Source Four produces light equivalent to a 1000 watt spotlight using previous technology. This lower energy consumption saves electricity and creates less heat. The HPL lamp also gives the fixture its name. The lamp (light source) has four filament strands, hence Source Four. It is available in 375 W, 550 W, 575 W and 750 W versions, at a variety of rated supply voltages. HPL lamps are also available in longer life versions that reduce the color temperature from 3250 K to 3050 K to give the lamp a life of around 1500–2000 hours as opposed to the 300-400 hour life of the standard HPL.