Push to pull compression fittings

Push-to-pull, push-to-connect, push-in, push-fit, or instant fittings are a type of easily removed compression fitting or quick connect fitting that allows an air (or water) line to be attached, nominally without the use of tools (a tool is still usually required for cutting tubing to length and removal). These fittings act similar to the way regular compression fittings work, but use a resilient O-ring for sealing, and a grip ring to hold the (possibly grooved) tube in place. With metal tubing, a groove is needed to hold the tube in place. With PTFE tubing, the tube deforms around the grip ring.