Convenient adjusting screw and a hardened steel locking ring are two features that make these 2,000 lb (907 kg) capacity JHV high jacks last for many years of use. Patented internal safety stop prevents injuries to hands and fingers. Roller head jack (JH2R) has extra wide bearing for greater strength (2,000 lb capacity) and tool life. Adjusting screw gives proper working height. Outer surfaces are powder painted or zinc phosphate plated to resist corrosion. 1,000 lb (454 kg) capacity ball transfer attachment (JTA) with replaceable ball casters bolts to either side of V-head. Ball transfer head attaches to RIDGID? brand and Sumner? models while all Reed heads (JTA, JH2R) and bases interchange with Sumner? and Greenlee?. All heads fit both high jacks and low jacks.