4-ply, double-lock bottom. Deep sidewall corrugation for strength. Heavy-duty zinc G90 coating withstands harsh weather conditions. 1-1/8" top rim is permanently rolled for strong reinforcement. 1" tube inside rim of tank for additional strength. Most feature a 1" drain plug. Unmatched quality and consistency in construction. Sold in nests of 3. 2' x 2' x 4'.