The SD Hoses Silicone Breatherhosekit(part no. SD21) has been designed to replace the standard restrictive OEM hoses on the Astra HVXR.The hose is constructed to provide a constant radius reducing restrictionthroughout the whole piping.The hose is made from high-quality 6 layer mutli-ply silicone. It is available in Black, Red, White or Blue to compliment the signature colours of the Astra HVXRrange.