It's not a pinch and fit, radiator clamp type of thing, and it's not a Fluval part. It is a contraption whereby you insert the hose and then tighten the connection by turning a large nut that the hose is sticking into... almost like a compression fitting for an airline, but made for plastic hose.
I saw it on a YouTube video, but can no longer find said video! It's driving me nutz!!!