All the other chain rollers of this size I have used have _two_ bearings fitted and a spacer sleeve in between to be the correct width. This unit only has one bearing fitted, and a metal sleeve to the other side! = Dodgy, Nasty! I'm going to have a friend with a lathe fit a second bearing for me before I fit it to the bike. Next time I will ask the question before I purchase as I never considered anyone would do this (fit just one bearing, not two). The things they do to save $1.