I'm with 5 shot; I used the same system this year with the lag bolt and the aluminum step which slipped over the hex-bolt end. It was simply awesome! I could carry the steps in and out with me, and hang each step on the already-screwed-in bolt as I went up the tree.

The little hex heads left upon getting ready to leave are almost impossible to spot while walking through the woods, and even if someone does see them, the only way they can get them is if they have a socket set with them (or some kind of big crescent wrench or something like that).