I was going to ask, what is that, 12 gauge?
(jk) BTW, what do you use for magnification to work on these? I just got my microscope last week and find that 20x is a bit too much; 10x would have been better. I might still order WF5X eyepieces to yield 10X when combined with the 2X objective. Got a 0.3MP USB camera with it but darn thing doesn't work. Pictures of these repairs would be good for your web site, or not, depending on how it looks.