The PU Equal Tube to Tube Connector is used for in-line connection of polyurethane or nylon air tubing of equal diameters. The quick connect fitting consists of gaskets and stainless steel grab-rings to grip tubing. The push-in collars and the body are made of polymer.Pneumatic fittings are components used in pneumatic pressurized gas systems to join pipe, tube, and hose sections. Tighter seals distinguish pneumatic fittings and reduced pressure needs as compared to hydraulic fittings. They're often found in pneumatic logic control and instrumentation systems.