Prevost 360 Degree S1 Swiveling CouplersDescription There is no other way to put this, Prevost Couplers are quite simply the finest in the world. This one is around $100, but I think it's worth every penny. It's a bit hard to explain how these work, but they have a press button soft release. Check the video above for a demonstration in operation. There is nothing else like this. This has 1 4" NPT threaded inlet and is Euro High Flow standard outlet sizing. Prevo S1 Euro High Flow Aluminum