The Simply Pond – Wren High Density Preformed Ponds are ideal for fish and wildlife ponds, are easy to install and are supplied with a 15 year guarantee. They are made from 4mm thick HDPE (High Density Polyethylene) for good rigidity and durability. Unlike sheet liner the finished pond will look neater without any unsightly creases. The Simply Pond – Wren has built in planting shelves. Simply Pond – Wren Preformed Pond Dimensions Longest Length: 134cm Widest Width: 79cm – Narrowest Width: 52cm Max Depth: 43cm Shelf Depth: 22cm Capacity: 180 Litres (40 Gallons)