It is prudent to keep track and to even consider a redundant system so that if your computer fails or the batteries go down you can still collect the information you need and to calculate standard tables as well, as you use the convience of your computer. Analog and Digital Gauges of today are very accurate and provide the necessary information needed to monitor air supply bottom times depths and navigation with compass. They come in single units to multiple configurations. Many are made in plastic cases and the better ones are still made in brass cases. They vary in the amount of depth units and psi units.
Digital units require batteries.
Some gauges are user adjustable. Find a Buddy-World Wide. Just click on the flag and go to our international area to find a buddy worldwide. Just click on the flag .