*Excellent* Olympus A 100 PO 1.30 Oil 1.60 /- Microscope Objective Lens 34056
The microscope uses BH2. Listed lens type / long neck objective lens / mount sizeRMS 20.25mm. You can judge the accuracy of the objective lens from the photo. Since it is a used lens, it is not inspected by enlarging it with a magnifying glass.