Air gauges come in a wide variety of styles and sizes. They also have different capabilities depending on the sensitivity of the task at hand. Some are used to give rough estimates of lengths and diameters while other are used to achieve an accuracy of up to +/- 0.02mm. The type of display used to give the readings also matters when it comes to the accuracy of results. Basically, there are two types of displays that are used to give readings in gauges. These are the analog and digital display units. Each of these displays plays a specific role when it comes to conducting measurements.
The analog display unit; which was used inn most traditional air gauges, is generally used to give rough estimates of measurement at a glance. However, some types have an inner scale that is used to give finer readings. Others have an adjustment knob that can be used to change the sensitivity of the instrument. The adjustment knob is used to change the scale in use (either from the outer scale to the inner scale or vice versa). Digital display units are known for their high accuracy and precision when it comes to giving readings. In most cases, they are used to give up to .001 mm readings that cannot be deduced from an analog display unit.
The simple types of air gauges have a single display unit and a single probe that is used to measure one dimension at a time. They are usually small in size, portable and can be carried around in the pocket. They are mostly powered by rechargeable AA size batteries or simple solar systems. The complex types on the other hand have a dual display unit (comprises of a digital and analog unit) and multiple probes that can be used to make numerous measurements at a go. They are generally bigger in size as compared to the simple types