To ensure the maximum life and durability from your Firestone EPDM 45mm Ribber Liner, we highly suggest that you preline the excavated area with Dewitt Underliner. This densely woven fabric will protect the Rubber Liner from rocks, tree roots, water pressure on liner folds, and anything else abrasive to the liner. Dewitt Underliner is only available in 15-foot widths, however we can cut any length needed in 1-foot increments.