Heavy duty forged brass body. Large all metal handles are angled for ease of operation. Floating piston, double o-ring valves for long service life and smooth operation. Silicone dampened gauges smooth out needle movement. Gauges can be recalibrated in the field to maintain accuracy MASTERCOOL brass manifold gauge sets feature durable all metal construction. Anti-flutter gauges give smooth pressure readings. Side mounted, metal hand valve will not crack when dropped. Gauges include R134a Fahrenheit scale in SAE and Kpa pressures. Metal bezels protect gauge lenses from breakage. R134a Auto A/C 2-way manifold gauge set with hoses in a clamshell package. Hose connections for blue and red are 14mm-M. Yellow hose is 1/2" ACME-F with auto shut-off valves. Gauges are 2-1/2" in PSI/Kpa. and come with shock-resistant gauge protectors.