I originally bought a davefab oil catcher, which had pretty bad design and build features that i explain in this thread. I also bought an IL motorsport one (that didn’t seem to be any different to the ebay offerings - no sight glass and also had missing welds. both of which went back.
I also had a davefab coolant tank ordered and found the same quality issues as with RichardFX (link)
I didn’t take the sight glass out but having had the oil catch can I wouldn’t be surprised if it was just threaded on the side of the aluminium coolant tank.
For the reasons above it went back, ordered the moroso one and never looked back.