I bought this new swing ring. It is approx. 2 1/4 across from inside to inside. The Slipring from rcwd will not fit insode this ring. You will need a slipring smaller than this one. The pinion gear is large thus taking up the space inside the ring. The ideal slewring would have an external tooth.....for that i am still searching. Also i purchased the slipring that is advertised on the KAT website.....it is not going to work either. The wires are somewhat bigger than human hair. and the turntable is about the size of 6 stacked quarters.
http://img02.taobaocdn.com/bao/uploa....gif_80x80.jpg
http://img02.taobaocdn.com/bao/uploa....jpg_80x80.jpg