Metal halide light bulbs come in many shapes and sizes. We stock many versions of the BT28 & ED28 type metal halides. These lamps come in 100, 150, 175 , 250 & 400 Watts. "BT" stands for blown tubular and you will notice these type metal halide bulbs have a small extended round tip on the top to support the metal tabs inside the lamp. The other type is an "ED" which stands for elliptical dimpled. The graphic below is a great example of the differnt styles of metal halide lamps available. If you are having trouble figuring out which lamp you need, please click the Live chat button or give us a call!