the platform is supported by 3 wood bars and 1 round metal rod(curtain rod left over from Ikea). The two middle wood bars will be permanently joint by middle board. Take close look the picture, the first wood is anchored by two twisted brackets, the two threaded holes are existing for the seats. Since the seat holes are with angle, you have to use pliers to bend the bracket in order to join to the 2x4. The second wood 2x4 attached two short legs which are sitting on sheet metal, for proventing from "jumping up", using tiewrap and metal wire hooked at existing square hole. The third wood bar is tied to two D rings by Velcro.