2.5/40mm lens OKS1-40-1, OCT-19 mount for Konvas, Kinor
The lens was made at famous LOMO factory in 1982 (#820633).
It has OCT-19 mount suitable for Konvas and Kinor Russian 35mm film movie cameras, but there are adapters on the market that will allow using it on other systems. Back focus is long enough to be used on modern DSLRs. Frame size is large enough to cover even still image full frame (24x36mm).
The lens has industry standard 32 pitch follow focus gear.
Mechanical is fine - both aperure and focus ring rotates smoothly.
Glass condition is good. No fungus or scratches, but there is is some dust, so the lens will benefit from cleaning.