The 6247 Replacement Xenon High Stability Lamp is commonly called a "Super-Quiet" Lamp. Most arc lamps suffer from "arc wander," the gradual movement of the arc point over time, caused by a lack of electrons emitted from the cathode. This results in the need to re-adjust the lamp, over its lifetime. This 75 watt lamp with a 1 x 1.5 mm effective arc size addresses the problem of the arc wander by using a high-performance cathode. The radiant intensity won’t drop off over the lamp’s lifetime. This lamp is compatible with the 66148 Socket Adapter (not included).