yes that is the same bulb that you would use if you had a 400 watt mh ballast. YOU NEED THE BALLAST, not trying to yell but just so you know. and yes they do put off heat, but if you have proper ventillation you should be fine. also depending on where you live your bill should go up 15-30 buxI was at home depot today i saw a 400watt mh screw in bulb. R these any good i am acfl grower and brand new t that. Do all mh bulbs screw in like cfls? Do they put off way more heat? Will my light bill b higher if i use ths? Thx