Pack comprises 4 x 320mm high sections that put together make a complete chamber which must then be filled up with concrete. All components lock together to make a robust chamber therefore ensuring the system is lightweight yet very strong.Chamber is made of recycled PVC (strong Polypropylene), and is recyclable at the end of use.There are knockouts to suit 60, 110 and 180mm pipes, and can be drilled easily to suit any other diameters.