I have 2 identical setups SUnleaves Artic Cool Lumatek 400W MH/HPS I got from ebay at a good price. SO why not have an extra? I didn't realize they were mh/hps compatible until I was reading the manuals. DO I just buy a MH bulb 400W plug it in or is there much more to this as far as connector type. My hps bulb looks like a regular light socket but maybe twice the size. Is there a size standard I need to follow when looking for a MH bulb to use in the ballast? ANother newb ? Thanks for the patience you guys have been great. Keepong in mind the connector to the bulb is that connects to the ballast is what I'm taking about. DO MH bulbs fit that socket and the ballast auto switches to power mh or hps?