Lenses are interchangeable, Holding the arms near the hinge, rotate upward to remove them. To reattach, you hook the top of the arm into the lens, then rotate the arm downwards. Easy to do, but hard to describe so have a look at our videos for more details. We’ve designed them for that perfect tension that holds, but can also release as needed (such as if they get squashed in your bag, they won’t break).
Email me and I’ll add a video. Cheers, JB