That looks like a TomTom fitting, the GPS clicks into the ring. I use one in my car but I would be a little hesitant about using it on the bike.
Maybe I'll try, it'll be sitting right between my legs so probably wouldn't go too far if it clicked out of the mount.
New avatar, introducing my new bike - 2012 Suzuki Boulevard M50 with trunk box and saddle bags fitted and small Givi screen
