I bought a couple of these covers, and they both went on nicely. They are snug to the RMR and don't add much bulk. Once mounted to the RMR they are solid and can take bumps. The mesh doesn't block much of the view and it does its job well.
Just make sure when you remove these to be gentle. I did break one of them when I removed it, but I didn't read the removal instructions and wasn't careful. Umbrella took care of me though. There probably isn't much need to remove these anyway.