I just received the Aliexpress clone as well and...
No, just no.
It is not silicone!
It immediately disintegrated under a soldering iron heat, I don't want to see what would happen if I tried normal flame test.
It's just so bad, it's the cheapest softened plastic, it holds no form, the mold lines have small slivers that keep rubbing off and the the material is so soft you constantly feel like it's about to rip and you're gonna bite through it.
Even if I ignore all the material and quality problems, it just doesn't work well. It holds the teeth only slightly apart and it requires constant effort to hold it in intended position. As soon as you relax your jaw and let your teeth apart, the whole thing goes past your teeth inside of your mouth.
I found it way more frustrating and distracting than fulfilling or restrictive.
Oh and btw, the strap I got with mine was not real leather either, even though it was very good quality, it's some sort of neoprene(?) with fiber lining. You can only see the lining at the ends and in the holes.
The strap was still slightly too loose even at the last hole, though, but that's easy problem to solve (if I was interested in salvaging this thing.
It was this listing:
https://s.click.aliexpress.com/e/_DFK8t2l
@
ltxrob @
slaafruben @
aznstefanie Can you double check that yours is actually silicone? You can test with a flame or heated nail. If you don't want to mess it up, you can try on the inside of the strap hole.