How it Works 1. Take two poppets lay them on their sides like flaps. They lock each other, offering minimum head loss until the coupling parts... 2. When the flaps are released and allow the bias springs to rotate them through a controlled arc... 3. Until they have moved through 90°, where they snap onto their seats prior to the coupling fully parting. 4. With 100% Shut-Off achieved the two coupling halves then part completely.