For hermatically sealed transformers, the brass body screwed to the tank , highly visible red indicator for oil level, max and min levels. You can see the oil leaks easily. With real nitrophyl float , Oring or flat gasket, tin or zinc plated body.
The radial movement of the nitrophyl float moves the magnet and it changes the position of pointer of the indicator. The magnetic oil level gauges serve the purpose of visually indicating the oil level in a tank or in a conservator of oil filled transformers
With glass ball or nitrophyl float and Brass body, R1"
This type of magnetic oil level indicator is used in hermatically sealed transformers without gas cushion. It shows the level of the oil in the filling pipe and possibility to monitor leaks from the tank.