TSA keeps an updated list online of their regulations restrictions etc. but I have noted variation among the screeners and the airports. The flashlight I carry is AA but I would not be afraid to carry the surefire lights with their 123's on board. If they ask you what it is for tell them its so you can see in the dark and look at them like any child should know the answer to that.
Oh and I have found that it is better to put every thing in a pack or bag not the little trays they have. It’s quicker and they only get to eyeball it on the screen not drool over you $100 light in the tray.