LOMO (Lenkinap) optical block of OKS1A-40-1 2.5/40mm lens
This is 40mm optical block for a lens purposed for 35mm film movie cameras.
It was made at Lenkinap (renamed to LOMO later) in 1957 (#571099).
It is in excellent condition. Diaphragm works fine (but you'll need to add a control ring for it).
Glass is clean and clear.
Diameter is 32 mm, length is 28 mm, weight is 72 g.