Key Features:
1. The interface of the sight glass complies with 3A standard.
2. The sealing ring is designed with a special structure, not easy to fall off.
3. Made of special glass, with high pressure resistance. 
4. The connection of the sight glass is safe and reliable, good strength, anti-vibration.
5.The material of glass: silicon boride glass or, tempered glass
6. Tightness test will be done before leaving factory.