If you need these push-in fittings with metal, please choice these.They are also in different shape, and only one hand can be
very convenient to insert the tube and pull out without any tools. The fittings with safty sealing and it's thermostable. 
In addition, these pipe fittings meetsrepeated insertion and pull-out requirement, when it gets
older along with the timed, this series can easily be replaced. 
Reliability: Rapid manual connecting and disassembling.
Compatibility: Works with the use of nylon, pu, teflon tube.
Adaptability: Hot and cold water systems, steam machine tool, lathe.

Varify the diameter and the thread to adapt to your tubings.