Hi, this is the flash diffuser that I have. I didn't buy it from this site but it is the same:
It works really well and I like it. They aren't totally plastic nor rubber, they are something like a compound between, and thus it is flexible; both the arm and the three diffusing caps.
Panasonic Lumix DMC-LS80
Canon EOS 550D
Canon EF 50mm f/1.4 USM
Canon EF-S 18-55mm f/3.5-5.6 IS
Canon EF-S 55-250mm f/4-5.6 IS II