Constructed from solid aluminum for added durability needed for repeated, tough daily use. Contoured easy to grip hand wheels are color coded for quick and easy identification. Improved face seal valves. Better design provides a tighter seal, less wear and improved flow. Proven, double O-ring piston design for extra reliability and longer service life. Easy to read 3-1/8" gauges protected by Lexan lenses. Aluminum Manifolds include sight glass. 1/2" ACME fittings with side R-134a hose holders.