Easy to turn on and off and easily "lock" your car key - just slide in and turn. I used three to replace the three OEM nuts holding the wheel to the bracket. If one is good, three should get the would-be criminal looking for an easier target. At least that's my theory. They look nice on the spare wheel but I wouldn't use them on a mounted road bike just because they stick out a bit which isn't a problem on a spare wheel as they stick out at the back. Standard quality mounted wheel locking loops are probably best suited for this application.