this is how people on Rddt are using it:
Looks like a silicone sleeve under it, but I'm not sure about the attachment; it seems to have these teeth that pinch your skin as you tighten it(circled in red) which looks like trouble. And besides that, I don't like the fact that I don't see my glans while using it, or touch it to feel the temperature/coldness.
Based on what I read about it, it was designed to be used for Peyronie's disease with an extender called restorex or something, so it's not designed for heavy-duty use.