It is the head assembly of Professional PT31 WZ40 Plasma Cutting Torch.
It is compatible with standard of PT31 WZ40 torch for 30-50A Plasma Cutting Machine.  
Rated cutting current 40A @60%, rated maximum cutting thickness 12mm.
Gas: Air.
Gas Pressure: 4.5-5.5 Bar.
Gas Flow: 150LPM.
Ignition: HF.