OC-12 
36mm orange lens filter
LZOS, USSR

Very good condition. Fully operational. Front glass has small scratches on the front (see photo #4). The rim has small signs of use.

Lens "Industar-22" is not included and shown as an example of mount.

This filter has 36mm mount and is designed for popular USSR rangefinder lenses: "Industar-50" (both for rangefinder and SLR), "FED", "Industar-22" and others. Filter does not have a thread and is set on the lens with friction force only (close-up). So, if a lens has a strong dent, this filter is probably will not be fixed firmly.
This is a classic orange filter with medium power, also it can be marked as "O-2.8x". It absorbs and neutralizes blue-green and violet light rays and increases the contrast of far objects. Blue sky becomes dark-grey at the images.
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Weight - 9 g
Mount (mm) - 36
External size (mm) - 37x9