A Glimmer of Hope

Ok, so I was working on figuring out one of the objective lenses today and I FINALLY found one of them online. Bear in mind I've been working on identifying three of them for days now. The one I identified was the LOMO microscope objective that's 40X spring-loaded EAB planar achromat with a numerical aperture of 0.65, designed for a 160mm tube, with RMS threaded nosepieces and a parfocal distance of 33mm. Now I have no idea what that means exactly. I have a vague idea but vague is all. I know this lens runs for $28.00. I REALLY need a microscope optics expert. I feel like this is the labor of Sisyphus eternally pushing a rock up a hill...