This is the highest rated disc lock (according to OnGuard's own rating system). If you want to save a couple of bucks, or aren't sure if your disc brake has a hole large enough to fit the 5/8" shackle then you can save $6 and get theOnGuard Boxer 5048 Motorscooter and Motorcycle Disc Brake Lock(1/2" shackle) which is just one step down in their security rating. Of course, any disc brake can't deter someone from simply picking up the bike onto dollies and rolling it into a truck - so the best bet is to chain the bike to something immovable. But if you can't do that, this lock is pretty much safe from hand bolt cutters and any direct attacks.The lock mechanism on all the OnGuard locks are first rate (I've owned at least 4)...unlike $50 Kryptonite locks which (the older models) could be opened with bic pens.