Poly Round End Tanks are made with a durable, seamless design that helps resists breakage. All round-end tanks have an extra heavy duty, molded rim and an extra-deep sidewall rib design for additional strength. A Heavy Duty, molded in aluminum drain fitting and 1 1/4poly drain plug ensure a long-life. All Poly tanks made with poly , tested to -20F, corrosion-free, impact resistant and recyclable.