3-1/8", 1% Accuracy High- And Low-Side Gauges That Both Handle Up To 800 Psi To Read Heat Pump Pressures And Transitions In Heating Or Cooling Mode large 3-1/8" Gauges Feature Steel Cases With Polycarbonate Crystal high- And Low-Side Gauges Read Up To 800 Psi-color-Coded Scales - Larger Dials Are Bold And Easy To Read dials With 1% Accuracy (Class 1) Full Scale Movement Provide The Level Of Accuracy Necessary For Critical Charge Systems proven Sliding Double "O"-Ring Pistons Reduce Wear long Life Nylon Seats forged Brass Body For Durability full Porting Maximizes Capacity And Flow full-Size Metal Valve Handles For Easy Operation hose Assemblies Ul Recognized For 4000 Psi (275 Bar) Burst And 800 Psi (55 Bar) Working Pressure (File# Sa9737)Made In Usa. Made in United States. Manufactured by Ritchie Engineering Co.