There is the Neotech Accordion Mega Harness that has additional ukulele comfort and support especially for heavy accordions. Its big, 2.75”x 21” non-slip shoulder pads do not shift around and thus does not require a back strap. It uses strapping of neoprene and a stretch system employed to minimize pain and dampening of movements for a loving play. It is simple to attach having top 3/4″ webbing and bottom Neo-Loops.