These are quite easy to install into a tank and depending on the thickness of the tank wall all you need to do to fit a Gauge like this is drill a hole in the tank about 8mm in diameter then insert the gauge and secure with screws.
Specifications Pressure:
Do not exceed gauge pressure. If you exceed gauge pressure it will damage the capillary in the gauge and prevent the gauge from working correctly.
NEVER exceed the maximum gauge display pressure range.
Not tested or approved for pure oxygen.