you need a 400 watt MH. they are all the same as far as working... ballasts differ in the incoming voltage needed, and being either electric or magnetic (yours) .. bulbs are pretty much universal (for a given type of light and wattage)
growinforthefuture Reviewed by growinforthefuture on . Need help figuring out which MH bulb to get! So when we got out HID system, we payed $50 and promised to smoke the guy up once. Not a bad deal. The hps ballast and light are being used, but the MH bulb burnt out when we first got the systems. So now I want to buy a replacement asap. The thing is I have no idea on the specs of these ballasts. I did some research, googled M400LU/HTL and found this website which had a spec sheet about the light which said S51 EYE Hortilux Metal Ace So then here I am on 400 Watt Metal Halide Rating: 5