Big clips and a nylon strap that is adjustable. They seem pretty secure, albeit fairly small.forgot to ask: the side bags are fixed to their own racks by big clips only? any secure plug?
I haven't tested them, but they are rubberized with Velcro closure at the top that folds over and strapped. I think they will be very water resistant.Looks great! How does the waterproofing seem on the bags?