The dial with a magnifier attached, whose scale is precise and the diameter of which is 45mm, can be revolved. The folding shell, cast by engineering metal alloy, with its 2mm average thickness, is very solid. You can use the compass scale in the proportion of 1:25000 on the side of outer shell to measure the distance on the map. In addition, you can judge the deflexion utilizing direction measure apparatus . A metal wire fixed on the cover is used to locate positions on the map or in the field. A secure button is designed to prevent the cover from opening itself. There is special oil inside the dial.