The pointer is rotating in a hydraulic oil for stable, precise and error-eliminating reading, even to a differential sub-vernier versus the annular graduations are read super imposedly with minimum reading error
Double annular graduations are provided for preventing wisual reading error
The transparent temperature-resistant oil may visually amplity the pointer for a better optical reading
The double-rail magnet may attract this angle level on a round pipe or a surface of ferrous material
An extension rule may be inserted into the bottom slot for measurement and drawing line for the wider area
