These have been cooked up in garages and home workshops for about 30 years, and we've taken the best features of the best of those, added one or two extras, and had Nitto bake up this for us. You strap your saddlebag to it, and it to the seat rails. Then you open the quick-release and walk away with your saddlebag, the handle still attached. So you don't have to leave it on your bike. Most of the time it's fine to leave it on your bike, but if you frequent the same haunts as ne'er-do-wells, you'd better use one of these.
Required item if you're one of the many whose saddle is bag loop less and you want to step-up to SaddleSack ownership.
NEW: The saddlebag grip now comes with self-tightening nuts so there's no chance of the hardware loosening up and falling off in the middle of a ride.