sight windows 1)measure ranges:300~2000mm2)work temperature: -40~603) working pressure: ≤4MPa4)needle switch close automatically pressure:≥0.2MPa5)defrost pin height: 100mm, 150mm,200mm, the lower the temperature the higher the pin.6)flange material: qualitative carbon steel or 1Cr18Ni9Ti TBS-C type defrost glass sheet liquid level gauges