I wanted something to connect the standard F6.3 celestron focal reducer onto T2 as there are many T2 connectors available, but so very few with the SCT 2 inch back thread. This works a treat, the outer connector fits onto the outside thread of the focal reducer. The other end is connected onto a baader varilock with T2 thread. In my set-up it adds 8mm to the optical path, but this isn't a problem, this may possibly different if you use some of the other threads inside the connector. Very happy with this as I've been trying for ages to find something that would fit. It comes as - an outer connector which holds the inner connector onto the focal reducer, a roughly 42mm diameter spacer and the inner adapter which fixes onto the T2 connector.