Two single sockets on separate switches and cords hold 2 incandescent lamps up to 150 W each. Perfect for holding a BrightLight (item# 674416 or item# 674417) for daytime basking and heat, or a NightLight (item# 674419 or item# 674420) for night heat. The 20" fixture sits on the screen cover over the reptile basking/sleeping areas.