The Silva Polaris 177 Compass is one of the most popular compass in general use today. The back of the base plate has a new contoured ergonomic design that fits your hand. Graduation lines and large numerals allow easy reading. Inch, mm and 1:24,000 scales. Declination correction scale. Dimensions: 2-1/16" x 2-7/8", weight: 0.8 oz.