One metric Blue GReddy Silicon hose coupling to connect different diameter piping (as included with GReddy Turbo and Intercooler kits for charge and suction piping.)  
3 ply (3.5mm) construction of Silicon and Nomex. Higher heat and corrosion resistance compared to the rubber hose. 

Available in stepped metric sizes:

 12400751     Dia. 42mm to 50mm  x L60mm 
 12400754     Dia. 45mm to 50mm  x L60mm
 12400757     Dia. 50mm to 54mm  x L60mm
 12400760     Dia. 50mm to 60mm  x L60mm
 12400763     Dia. 54mm to 60mm  x L60mm
 12400766     Dia. 60mm to 65mm  x L60mm
 12400769     Dia. 60mm to 70mm  x L70mm
 12400772     Dia. 60mm to 80mm  x L70mm
 12400774     Dia. 65mm to 75mm  x L70mm
 12400775     Dia. 70mm to 80mm  x L70mm
 12400778     Dia. 78mm to 100mm  x L100mm
 12400780     Dia. 80mm to 90mm  x L70mm

   *For Straight Hose see: () and Boost Clamps ()