We would like to get some frame bags (1 for stoker, possibly 1 for captain) that fit in the open space under the top tube. Our frame is open with no laterial bars. I have seen these before but have never had the opportunity to talk to the people using them to find out what brand they are. Some are kind of angular shaped. One model is the Relevate Tangle that is sold by Adventure cycling, but we have seen others that might actually work better. Do any of you use these, and have photos or brand names I can search for? I see tandems east has a couple, but honestly I like websites that show you all of the specs (dimensions, in this case) and give you the opportunity to order online.