This is a nicely mounted PCX lens with a 38 mm focal length and a 14 mm diameter clear view through the assembly. The mounting is an anodized ring 18.5 mm diameter and 5 mm thick.There is also a step with a diameter of 16.8 mm that could be used to mount the lens on the end of a tube. These could be a good choice for an educational lens, since the glass is completely enclosed by the ring, and can't be disassembled or easily broken. We have a large quantity, so start designing something around this item! New, old stock.