Adam of the Amazon Live events shows them in use.
At 3m11s the question is asked of Adam of prescription and Adam replies basically they aren’t doing them but you can go to your local service and get.
You also see them being pulled apart and attached and the box. As I guessed above it’s a friction mount so a spring like mechanism. So this is quite a lot of information, may help those who are hesitant to order.
The latter half of the video Adam gives more information about the L3P.
The web page where you see what you look like is really clever. I tried it on some household items, the pet, etc and it could tell not human. I then pointed at the TV and look what happened. Recognise the lady in pink? What’s she wearing? If this causes offense I’ll delete.