STKUSA A/C Manifold Brass Gauge Set R134A R12 R22 R502 Easy to read gauges with 4 PSI scales (R134A, R22, R12, R502) and Celcius scale 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 Convenient hook allows for the manifold to be hung in place Can be used for automotive or household air conditioning units