Arguably the most resourceful compass in the world for artillery; target acquisition and command posts, the 55 is a unique compass featuring both an optical precision sighting system and a SILVA 1-2-3 SYSTEM Compass in the same unit, giving unbeatable precision and versatility in the field.
Bearings can be taken with accuracy to within half a degree. The compass has a luminous graduation ring and markings for compass reading in the dark. Once activated by daylight/flashlight it will give light up to 4 hours of light. 6400 mils on the graduation ring and 6400 mils + 360 degrees on the sighting scale.
Graduations in Mils (Milliradians):
Mils compasses are divided into 6400 divisions rather than the standard 360 degrees. Mils compasses are largely used by the military for calculation of range and scale – for example two objects that appear to be 100mils apart and are 1000m away from the observer are around 100m apart on the ground.