OP895151
It was originally a small 24-inch - wheeled (yes, not 26-inch) rockhopper mountain bike frame for kids / adolescent, which I chopped in half to make it a folding frame. It couples using a method similar to but different from the Ritchey breakaway, a DIY version, with a sleeved tube for the down-tube coupler and a cut seat-tube with an extra seat-binder brazed on for the top coupler. Very unique one of a kind thing.