Red
Round T-bag mounted to OEM Sissy bar/backrest. I have 3 sissy bars. Tall, medium and OEM. This T-Bag mounts perfectly with the OEM mount, with the excess tucked inside. It is the normal mount I use for around town, etc. large enough for frogg togg rain gear, first gear rain cover for gloves, 1/2 liter MSR gas bottle, first aide stuff, extra gloves, jacket liner, windbreaker jacket, lock, spare key, streamlight scorpion flashlight, leatherman, tire kit, and other stuff.
On my CVO Rally trip the OEM sissy bar/backrest will be replaced with the tall one and I have the older style touring T-Bag that mounts over it. Actually quite stable kinda made for each other. I normally reverse mount the T-Bag so it rests on the seat and I have a back rest and that then allows the touring T-Bag 1 cuft round bag (not the one in the pic) to rest on my luggage rack.