The two models, which make up the M-Series (M-2, M-3), represent durable, reliable, high quality navigational aids, which perform flawlessly in even the most demanding of conditions. Both models feature a large liquid filled capsule and adjustable declination correction scale. Another convenient feature of the models in this series is the serrated bezel ring, which is easy to turn even in cold conditions while wearing gloves. Due to their easy-to-read luminous markings and magnifying lenses, the compasses of the M-Series are also ideally suited to navigating in conditions of poor visibility. The M-3 model is also available with the Global Balancing System.
Field compasses in general
Mechanical compasses have been working as the navigator since several thousands of years.
Still today magnetic compass is environmentally friendly, cheap and the most reliable tool when choosing the course. The oldest Suunto field compasses, which are still in use, are manufactured in 1938. A high quality field compass hardly needs any other service than washing in fresh water from time to time. The compass works without any external power supply. The compass gets its power from nature from the magnetic north pole.
Two Geographical Balancing Zones
The vertical intensity and direction of the earth's magnetic field, the inclination, influences the horizontal plane of a compass needle according to the latitude where it is used. Due to inclination, compasses must be balanced for different geographical zones in order to keep the needle in a horizontal position.
Previously, the globe was divided into five different balance zones in which specific compasses functioned. However, as people travel more and more, the need for a compass with a greater geographical range has increased. Thanks to Suunto's 'Two Zone System' there are only two balance zones to consider in compass use - the northern hemisphere and the southern hemisphere. In practice, this means that a Suunto compass designed for the northern hemisphere will still work for a fair distance into the southern hemisphere, and vice-versa.