The Apeks submersible pressure (contents) gauge, with an internal Bourdon pressure measuring mechanism, gives you clear information on the gas contents of your cylinder. The gauge indicates the cylinder bottle pressure and the dial range is from zero to 5000psi (a metric version is also available with a range up to 360 bar). The dial face is designed with clarity in mind by being uncluttered, with large black figures on a luminous background giving a long phosphorescent effect. This makes viewing as easy as possible, even in poor visibility conditions.