The blagdon all you need pond lining system is a combined pre packed pond liner and underlay kit for constructing your garden pondr the liner is a 05mm pvc liner with a lifetime guarantee this is complemented by the synthetic underlay which prevents damage to the liner and will never rotr to work out the liner size requiredr liner length maximum length of pond 2 x maximum depth of pond 50cmr liner width maximum width of pond 2 x maximum depth of pond 50cmr this pack is suit