1 metre of 10mm Polyplumb polybutylene grey plastic barrier pipe.
Buy as much as you like (up to 50 metres) and get it all in one continuous length of pipe. For example, buy a quantity of 5 and receive one piece of pipe 5 metres long.
Polypipe recommends the use of a metal or plastic pipe stiffener.
Polyplumb is suitable for use in most plumbing and heating installations including hot and cold water and underfloor heating applications.
More information and instructions are available from the manufacturer www.polypipe.com