The most important criteria a diver should look for in a regulator is ease of breathing. Computers Even though you've been certified, chances are that you've never had the opportunity to use a computer. Using the standard dive tables, your dive time is calculated on the lowest depth reached for your entire dive time. Even if you were only at that depth for 2 minutes. A dive computer will allow you more dive time by continually calculating your changing depths and the nitrogen absorbed at that depth.
Different computers use different mathematical models.
These range from conservative to more liberal dive profiles. The more conservative your dive profile, the less likely you'll get decompression sickness. There are lower costs computers that have less functions and features. Some of the features you should look for in a low cost computer include easy to read, manipulate and understand, graphic display, display of nitrogen levels, time available, and ascent rate, ability to make the limits more conservative, warnings for decompression violations. It's also important that complete and easy to understand instructions are included.