All the basics for charting and navigation functions are found in the Primary Navigation Set. This mix of tools for navigation is a tremendous value. Features our best selling UltraLight Divider for measuring distance, a milled 12in. parallel ruler for determining accurate course lines, the Nautical Slide rule for speed and distance calculation and a navigator's pencil. #176 - UltraLight Divider/Compass. #139 - 12 inch Parallel Ruler. #105 - Nautical Slide Rule. #1141 - # 2 Navigator Pencil. Durable plastic storage pouch.