This SPG is the perfect size and style for use as a primary gauge (either coming from a set of doubles or a rebreather). Some consider it to be a bit large for use with stage/bailout bottles in which case we offer our Thin Line SPG's as well.
The advantage of a glass faced gauge is that it greatly reduces gauge face scratches when compared to plastic faced gauges.
The gauge face has a glow in the dark background and large, easily readable pressure marks in PSI.