The Ultra Sun 1000 Watt Metal Halide Double Ended (DE) 6,000K open rated lamp emits a blue spectrum that boosts foliage growth during vegetative cycles and encourages tighter nodal spacing. 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. This bulb features a dual jacketed construction that allows it to be used in an open or closed fixture. For horizontal operation only. The jacket of this lamp is made from quartz glass. Oil from your hands can damage this lamp.