Type: Baseplate Compass, sometimes known as a directing compass. Baseplate: Fully transparent to allow placement over maps and viewing of details underneath, it features measuring scales (in centimeters and millimeters) on the sides for measuring distances on the map. Rotating Bezel: Contains direction degrees (360 degrees) and allows you to set the "angle" or direction you want to travel. Sighting lines: The parallel black lines inside the compass capsule help you align it with the longitude lines on the map. Direction Arrow: The small red arrow in the center always points to magnetic north. How to use? This compass is primarily used to relate the real world to the map; you can identify the starting and ending points on the map, then adjust the compass to give you the "bearing" (angle) you should follow to reach your destination accurately.