The instrument has a metal case in chromium plated brass and is therefore extremely strong.
The front glass is made so that it also acts as a pressure relief valve. In the event of a sudden increase in pressure inside the instrument, the glass rises slightly, allowing the excess pressure to escape.
The luminescent dial is calibrated up to 350 bar in the metric version and 5000 psi in the imperial one. The area below 50 bar is highlighted in red, the one between 50 and 200 is green and that from 200 to the end of the scale is light blue.