Had quite a bit of trouble fitting the first sight glass, had to carefully sand down the bushing to round off the edge which had to be pressed down as it was too big and had a few small burrs that got in the way. Also the fit leaves a lip instead of sitting flush like the OEM (see pic) which didn't bother me but thought I'd flag it for others. The second sight glass had a bubble in the glass/Lexan and could not be placed on the customer's bike. Now I have to wait a month to get another one…