You just stick an allen wrench from your multitool through it (side to side - there is a hole on the side) and turn. Or you can use a wrench or socket on it as well.

You get two when you buy a set. I took one, put a tie wrap through it and clipped it to the hinge on my toolbox in the garage. The other one went into the repair pack and I tie wrapped it to the seat bag with the tiniest tie wrap so that it would be easy to take off.

J.