Man, those straps really look great. Too bad someone over here doesn't carry them. Those piggyback straps would be very useful. Sure beats bungee cords. My tail duffle has d-rings & straps to attach to the bike and to attach other gear or bags onto it. But, it isn't waterproof & none of the dry bags have any attachment points.
wolfman makes a drybag with straps to mount to the bike. A little small though but would probably suit most peoples needs.
