NFPA interchangeable high pressure hydraulic cylinder product line. Time-proven 3-groove piston with cast iron rings outboard and a "GT" positive seal in the center groove. Each assembly is proof tested (as a pressure vessel) at 5,000 psi. More than 20 mounting styles in 14 bore sizes from 2½ to 5 in. are standard. Standard rod diameters range from 2½ to 3½ in.