Push in/Hold Farel/pull Out
They are Whale fitting and they work great and can be used over and over. The trick to release: is push Plastic hose in and then push farel in or hold in, then pull hose out while holding farel in. It takes three hands but with practices two hands can do it. The farel(I don't know the correct spelling) holds the tube into a Oring with little wedges the harder you pull on the tube the tighter the farel bits into the tube by pushing in the tube and farrel at the same time it loosen up the wedges. I hope this helps