Feature:Designed for Polyurethane or Nylon tubing.Even after installation, the direction of the tube can be changed freely.2 end O release ring help to connect tube easily by manual, no special tools required.Outside (and Inside where applicable) hexagonal wrench tightening.Applications: Mainly used for air compression systems, vacuum systems, pneumatic systems.Specification:Function: Bulkhead Union Air FittingsMaterial: Plastic, Brass Nickel PlatedThread Size*Pitch: M16*1.02 End O Ring Inner Diameter (for Tube Outer Diameter): 8 mmOverall Size: 51.5 x 31.5 x 22 mm / 2 x 1.24 x 0.87 inch (L*W*H)Package Content:1 x Quick Fittings