10205W Omega 20 Ton Side Pump Hydraulic Bottle Jack: Hydraulic system is protected from internal damage by a by-pass mechanism U.S Patent No. 5,946,912. Machined and polished cylinders with die-cut steel with die-cut threads provide non-abrasive leak-free, durable performance. Fabricated from hard-cast steel with heat-treated critical stress areas. Unique cross-type forged release valve assures positive load control. With a wide, rugged base providing stability and strength.