This adapter allows you to use Zenit/Praktica M42 lenses on your Konvas-2M camera. Due to necessity to match flange focal distance, we had to protrude it inside the camera. This causes two problems:

I have only three M42 lenses at the moment. All three fit the adapter and focus fine. Focus and aperture rings of Industar-50-2 and Helios-44-2 are accessible. On the Zenitar-M, aperture ring becomes inaccessible since it is located too close to the mount.

You should check dimensions of your lenses before purchase. Depth of the adapter is 19mm, inner diameter is 64mm. Make sure that your lens is slim enough in its rear part to fit the adapter. If not, you still can use this adapter in reverse direction, but you'll be able to use the lens in macro mode only, and aligning of the optical axis may be tricky.

Also, this adapter has no stop ring for instant return diaphragm pin. Your lens should have manual aperture mode switch.