Ideal for deep water fish and invertebrates. The 20,000 Kelvin flouorescent lamp is a high-intensity purified super daylight lamp that simulates light in deeper waters. It casts a blue-white glow allowing light to penetrate deeper into the aquarium. The metal halide lamps are designed to reproduce natural light conditions found in the ocean. The exceptional color renditions of these lamps bring out the most vibrant colors and provide ideal light required for plants and reef environments. Replacement lamps for traditional probe-start metal halide ballasts with an ANSI code of M57, M58, M59 and mogul-base socket fixtures. Dimensions: 1.75""L x 8.5""H.