Silva Expedition 4 represents the essence of advanced outdoor navigation. The Expedition 4 has a large baseplate to improve handling on maps and charts in the field. A full-sized baseplate not only makes it easier to hold you compass steady on a map, it's also easier to plot a bearing and take measurements. Silicon rubber feet for precision map work. Detachable safety-release lanyards. Night-enabling luminous markings. Large magnifying lens. Map-measuring scales in mm or inches. 1:25,000, 1:50,000 and GPS scales. The Expedition 4 can also map-measure 1:40,000.