 There are many compasses available for purchase. The most commonly used compass in forestry has a bezel, a rotating magnetic needle, and a siding mirror. The bezel is a rotating outer ring that is marked with degrees from 0 to 360 and most often in 2 degree increments, or it may be marked in 90 degree quadrants. If the bezel starts at 0 at due north and progresses around the face to 360 degrees, this is an azimuth compass. The rotating magnetized needle is always pointing to a location on the earth known as the magnetic north pole. The magnetic north pole is located near the true north pole, which is at one end of the imaginary axis on which the earth spins. The siding mirror improves your ability to take more precise readings as you navigate. When the mirror is partly open, you can look through the side at the top and also see the face of your compass.