Looks like an ordinary thermostat housing, but it is metal, not plastic, so it won't warp like the R....r one.
As far as i can see it MUST be fitted with cold (and hot) in at the middle as shown in the catalogue, because it actually has TWO flanges, one opens to allow water to the Hot outlet, and at the same time closes the Cold outlet. Works ok for road use, will add to this when we are able to have a thrash at a track day!!