GOOD QUALITY: The product is made of high quality glass and metal, which is durable and has a long service life and can be used for a long time. Sleek, modern oil level gauge with clear glass window Uses and purposes: Monitoring the oil level of screw air compressors UNIQUE DESIGN: The mirror sight glass adopts transparent window design, you can see the inside of the glass clearly. Professional service: If you have any questions about our products, please feel free to contact us, we will provide you with the best service.