Davis Mark 3 Sextant 11 with Davis Artificial Horizon 144 Navigation Bundle (2 Items). The Mark 3 is a plastic training sextant that comes with an instruction booklet. The 132 is a complete Celestial Navigation System Chart including Sextant Use and Corrections. The Artificial Horizon comes with 2 sun shades, lid and full directions. Great for backyard practice. Find exact position when inland and making exact sextant shot on foggy mornings. To use, fill with water and read the angle of the reflected sun with your sextant. Half your sextant reading is the sun & angle above the true horizon.