This sight gauge is an authentic original equipment part for Rolair air compressors. The sight is used to measure the oil level in the compressor pump. It is made out of durable clear plastic material, and is sold individually. Sight gasket is included part number 30500130CH.
The oil fill plug/breather allows you to check the oil and also allows airflow if the pressure becomes too high. It is made of plastic and is priced individually. The plug attaches to the II stage pump less flywheel and is used in Rolair compressors and pumps. A wrench may be needed to replace this part which is an OEM sourced directly from the manufacturer.