Polyconn's Duratec Pipe is flexible and is easily bent by hand and will maintain its shape and will not sag like rubber hose. The Duratec fittings have a double O-ring seal ensuring a leak free system and can be assembled / dissembled quickly with no training or equipment required. It's 75% lighter than the equivalent diameter of copper & SCH 40 carbon steel making it easy to work with.  

Duratec is made with a tough outer HDPE plastic layer, aluminum middle layer and a HDPE inner layer. This guarantees consistent system pressure for many years. The exterior protects against corrosion and deterioration, the interior is unaffected by inert gases and commonly used compressor oils. The fittings are industrial nickel-plated combining with the pipe will give you years of service.