Purchased for use the MeikeMK320. On the back, it has a hole with a rubber that is worn on the flash. The MK320 is small and thin, so it doesn't tighten the rubber and needs a Velcro strap. I suppose it fits better on larger flashes, it fit much better on an "ancient" Sunpak522.
Otherwise, I didn't see a huge difference, from the little I used it, compared to their plastic flash diffuser. However, a test will be done with glossy objects and that's where its fate will be judged.
It consists of two sections that fasten together with Velcro. It folds and fits in a jacket pocket when not in use.
Not a waste of money at the price of €15, you can use it if it tightens well on the flash.
I do not recommend it for small flashes, as the hole with the rubber is quite large.