Compasses that use a mirror are useful for finding the direction of an object within your sight. You can do this in three easy steps.
Point to the object you want to travel to. In this example, the tree is the object you are traveling to. Notice that the magnetic north arrow and the orienting arrow are not lined up.
While looking at the object in the mirror, turn the bezel until the orienting arrow and the magnetic north needle are lined up and are on top of each other.
Read the bearing to the object at the index line of the compass. The bearing to the object is 46 degrees. You can now walk to the tree on a bearing of 46 degrees.