A special feature of oil level indicators GN 650 is that the liquid level is visible even from the side. The polyamide body consists of two parts which are ultrasonically welded together. The oil level indicators are individually air pressure tested for leaks at 3 bar. Oil level indicators GN 650 can also be used on tanks which are pressurised. Pressure test results regarding resistance under pressure are available. As a contrast screen, a white lacquered aluminium strip is used which shows marking lines or temperature scale. The scale is placed behind and outside the liquid column as a protective measure. The shape of the oil level indicators offers a magnifying effect which makes the scale easily legible.