Nautical Slide Rule Gives immediate solution to all speed-time-distance problems. Equally applicable for nautical or statute miles. Speed in knots or m.p.h., time in hours, minutes or seconds, distance in nautical or statute miles (or yards if desired and if speed is in knots). Easy to read and accurate. Standard in U.S. Navy. Dimensions: 7-3/8" square. Wt. 5 oz.