I have to disagree with the baglux lovers, I think they look hideous. Why have a lovely painted tank and cover it with tarts handbag pleather?
Get your self an SW Motech Quick lock system or the new Givi equivalent, they don't touch the tank or cause any marks to the paint.
SW Motech Engage tank bag (they do bigger and smaller versions)
Quick lock attachment fitted to fuel cap surround.