ARKSEN 4Valve Manifold Gauge, Hi/Low Adapters, Brass HVAC A/C, w/Carrying Case Black Heavy duty aluminum manifold body is highly durable and lightweight The built in sight glass allows you to see if the system is functioning properly and when to change the charging tank Vibration resistant gauges feature a flutter-free design with provides accurate readings Easy to read 2-7/8" gauges feature 3 PSI scales (R404a, R410a, R22) and Fahrenheit scale Color coded hoses help identify the hoses for added convenience