Since 1967, Suunto has offered its KB line of high-quality hand-bearing surveying compasses and inclinometers that are accurate to fractions of a degree. These compasses are popular among cave explorers, foresters, geologists, archaeologists, land surveyors, and mariners. Traditionally made of a solid block of machined aluminum (some newer versions are in high-impact plastic housings), each KB compass contains a magnetized dial with calibration markings printed along its outer edge. A prismatic sight (KB-77) is mounted at one end of the instrument with a crosshair providing a view of the disc, containing both forward and reciprocal bearings. In operation, the user divides his or her field of vision with the instrument, using the device's prism to precisely measure the bearing of the object in view.