The Blagdon Ultimate Pond Lining System are combined kits of pre packed liner and equivalent underlay. Take the confusion out of how much linerunderlay is required.This 2.5x2.0m 8' x 6'6 set is perfect for creating a pond 1.0m x 0.7m x 0.45cm deep 3'3' x 2'3 x 1'6 pond volume 315 litres 69 gallons.