Order Custom sized liner for closed, container garden or open top systems. Double ply of 6 mil each LDPE non-outgassing plastic. Fittings can be placed as needed anywhere. Bag expands to 18x18” and can be cut and sealed up to 200 ft. long. The length required for a given tank is 18” for every panel wide, but you must include an extra 36” for the “end cap” of the tank or 90° turn. 180° turns require an extra 72” but is not recommended due to the bag closing itself off.