I was dubious..but it really works very well. The back case (which is very thin and a nice accessory in itself) has a metal female screw-in. The lens screws into this, and the tripod screws onto the lens. My only concern is the receiving unit on the case the lens screws into is brass. You have to be careful or you can strip the threads.
The lens is a manual focus..it would be nice (but expensive) to have an electronic focus. But the pictures it takes are clear. By using the magnify on the iphone plus the lens you get a very detailed telephoto. Then once the picture is taken you can expand it yet more, to multiply the 12x to much more.
The whole setup comes in a nice velvet pouch for storage. I was also amazed that this item came from China in like 2 days. How do they do that??
Here are 2 photos...one without tele and one with tele (and squeezing iphone camera option)