Brewfitt Celli Eric inline chiller advice needed

[Crankwood]

I have a couple of inline beer chillers made by Celli for Brewfitt and could do with a bit of advice. I believe that unlike my Cornelius ones they don't have an in built pool but instead have a large diameter water in and water out connector. What do you connect this to? They seem better than the Maxis as they have a built in variable temperature controller.