This adapter allows using Rubin-1 lens (and other lenses with Soviet version of DKL mount) on cameras with universal M42x1 thread.
Machined of high quality aluminium alloy.
The adapter allows the diaphragm opening change, but it does not have aperture values scale. To operate the diaphragm, you should loose the adapter thumb screw a bit, turn the ring to adjust aperture value, and tight the screw again.
IMPORTANT: the Soviet version of DKL mount is mechanically the same as original Western version, but the flange focal distance is different.
You can install this adapter onto a Western lens with DKL mount, but you will not be able to reach infinity focus then.