With a 20-30% more light output per watt, the Double Ended Grow Lights are quickly becoming the top choice of commercial and serious growers alike. All of our Double Ended reflector and ballast combos are compatible with both double ended HPS (High Pressure Sodium) and double ended MH (Metal Halide) bulbs. There are a number of advantages with Double Ended Lights over Single Ended Lights- 1. Since it's supported by both ends, there is no need for a metal frame, making the bulbs ultra thin. The thinner profile of the bulb increases the light delivery and improves the optical properties and results in a much higher light output compared to its Single Ended counterpart. 2. Unlike single ended bulbs which are recommended to be changed after every 6,000 hours of use, the DE bulbs retain nearly 90% efficiency after 10,000 hours of use. 3. Because electrical current travels from one end of the bulb to the other with the DE bulbs, it is far more efficient than SE bulbs where the current has to travel in a loop.