Ergonomic explorer: Ergonomically designed base plate comfortably fits hand while 1:24,000 and 1:62,500 direct reading scales ensure accurate mapping and plotting. Extended base plate has inch and 1/10-mile direct reading scales that meet U.S.G.S. standards. Features: 2° dial graduations. Built-in magnifier for map details. Declination scale for quick adjustments of map bearings to field headings.