This adapter has two functions:

1. Allows using M77x0.75 filters on lenses with 65 mm outer diameter.
2. Allows coupling such lens with a matte box with 80mm opening.

Known compatible lenses are:

1. LOMO OKS3-22-1 in Konvas housing.

Made of anodized aluminium. Front 80mm plastic snap-on cap is included.

This is improved version:

1. Flat spring installed to protect a lens barrel from damage by set screws.

2. Front part made shorter to reduce risk of vignetting with filter installed.