After reading lots of guides online I was initially concerned about ordering just one jar for my broken Mitutoyo jar. All recommend buying a special press for inserting the glass back. But the bezel came off immediately, and a light press of a finger was enough to remove the lens and put a new one back in. Now all that's left to do is show all the guys at work how it happened because they all had cracked lenses on their calipers. (I think that's common with the Mitutoyo 505 series.) But $9 is a lot cheaper than a new pair of Mitutoyo.