I bought a T-Bag on Craig's List. It does have an elastic sleeve to fit over a back rest, but also has straps that can be attached to other parts of the bike. The sleeve was too small to fit on the rather large Thunderbird back rest so I took it to a luggage repair shop and they did a perfect modification job. I bought Triumph saddlebags at the same time that I bought the 'Bird. They look great, but barely hold my lunch bag. The T-Bag is great. When traveling solo, I set it on the passenger seat with the sleeve over the back rest. If I have a passenger, then the bag sets on the mini-luggage rack with the sleeve over the back rest. I have the Triumph long-haul dual seat.