The Ultra Sun? 1000 Watt Metal Halide DE 4,000?K lamp emits a blue/white spectrum that can be used during all stages of growth. Specifically designed for high frequency DE ballasts. DE lamp construction incorporates the electrical connection at each end of the lamp, removing the need for a frame inside. The absence of the frame eliminates shadows in the beam. For horizontal operation only. The jacket of this lamp is made from quartz glass. Oil from your hands can damage this lamp. Must be used in an enclosed fixture with a protective lens. Do not operate in an open style luminaire.