The 600 crank on my wife's Fuji mixte has them. The BB spindle is marked "for use with self-extracting bolts" or something to that effect. It looks like a perfectly ordinary ordinary spindle, otherwise. I think those bolts can be used on any crank with 22mm threads. They hold the arms on like any crank bolt, so I don't see how they could have a tendancy to loosen. The only difference is that they push the arms off when the bolts are backed out.