This Replacement for GE 44057 LU400/D/40 is a 400W high pressure sodium (HPS) HID lamp designed for reliable, high-output performance in outdoor and commercial lighting applications. Featuring an E40 mogul base and ED white glass bulb, it installs easily into compatible fixtures using an S51 ballast system. Delivering approximately 42,750 lumens of 2100K light, this lamp provides powerful, high-visibility illumination ideal for street lighting, security lighting, parking areas, and other large outdoor spaces. Its 11.31" length ensures proper fit in standard HID fixtures. With a rated life of up to 24,000 hours, this Lucalox HID lamp offers long-lasting durability and reduced maintenance needs, making it a dependable choice for continuous outdoor lighting applications.