Helios 44M ring.

Ring to put inner lens of Helios M44 a little bit near the sensor so you can focus to infinity using F-mount to M42 adapter.

You can see why and how to make mod to your Helios 44M in this video:

Here you have two ring one 1 mm thick and othrer 2 mm, to use depending the adapter you are using. In my case I'm using 1mm.

Warning ans disclaimer: I'm not responsible for any damage you make on your Helios 44. Do at your own risk.