Davis #64 Course Plotter Carries map distance scales for nautical miles on 1:80000 and 1:40000 ratios maps. Aslo features map scales for statute miles & kilometers on 1:80000 ratio charts. Includes extra large protractor for measuring courses and bearings by utilizing meridians of longitude for alignment. Parallel lines are accurately spaced at 1/4" (6.4 mm) intervals, making inch scales available at each end of the plotter. Instructions included. Made of durable, flexible and virtually unbreakable plastic for use on uneven surfaces. Measures 15-1/8" x 4-1/6" (38 x 10 cm).