Length of metal cylinder

What is the length of metal cylinder used to focus 20W laser on ortur Master 2

If you want to make a reference for your focus, you need to do a ramp test and measure the exact height of your particular laser. It is very easy and the best way to find the right focus au one’s machine.

I believe it is 29-30mm, however please do what Bernd suggested

Thank you so much. Your reply was just what I needed.