You use the guide to measure from the base of the laser’s metal mounting bracket to your material.
I’ve been testing with the G2 lens. The 7mm spring goes in the laser unit and then the lens in the focusing ring is next. It took me a few tries to get it started. For the G2 lens you “tighten” it until it is almost all the way. When you test the laser you should get a dot. If not adjust as needed.
I’m still learning and I hope that helps.
Don