Apple’s latest and greatest smartphone is now available to order online through Apple’s website or one of Apple’s partner carrier websites (AT&T, Sprint, and Verizon in the U.S.). If you’re after one, you might want to grab it soon; supplies of specific models are said to be severely constrained.

If you don’t want to order online, you can also pick one up at an Apple retail store or carrier store later today, but be warned: the same supply constraints apply in those situations. Some stores are said to have received little-to-no stock of certain models. If you aren’t in line already, you may not be able to get the phone for now.