The military issue lensatic compass is used by our troops to help them navigate in the field. Although GPS has come into play as of recent, this type of magnetic compass is still the main stay. Satellite failure or grid blowout would make GPS non functional and then what do you do. You pull out your phosphorus or tritium GI military marching compass to save the day . They are measured in mils and degrees and feature a site to help you shoot a coordinate.