Parallax Adjuster Ring Helper

This is a helper ring to fit to my Nikko Sterling telescopic sight fitted to my air rifle.
It's designed for my 50mm AO Objective lens.
It's printed in ABS but no reason why PLA wouldn't do I suppose
The one I printed was quite a tight fit but some earlier ones were too loose so you may need to take the edges of the radii off with a bit of sandpaper depending on how accurate you printer is.