This device is a plastic PG style pneumatic fitting connector with 8mm to 4mm reduction. 
Specification:
Type: Hose to Hose
 Connector Type: 4mm,6mm,8mm,10mm,12mm,14mm,16mm OD Hose
 Design: Straight Shape, 2 Ways
 Fluid Type: Air / Vacuum
 Operating Pressure: 0~10.2kgf/cm2 (0~1.0Mpa)
 Negative Pressure: -750mmhg (10 Torr)
 Operating Temperature Range: 0~60C
 Fit For Tube Material: PU / Nylon, Polyurethane
  
 
    
             
  
 