Any idea what this is? It came bundled with some other hardware.
It looks like an eyepiece, but it's too big for 1.25" and too small for 2".
No compression marks on the barrel, and there is an inside thread. Maybe an eyepiece for a spotting scope?
Sometimes with 40mm eyepieces the field stop and maybe field lens is within the barrel. I don’t have this particular eyepiece and I cannot tell from your photos.
One good use for the upper section is as a desktop magnifier/loupe. I keep half a camera lens on my desk at work just for closeup inspection/ usually of very small text on labels. Sometimes it works better in reverse depending on lens design.
