Davis Mark 15 Master Sextant [026]Mark 15 Sextant #026 This model has many great features including seven large sunshades, a 3 mm x 27 mm star scope, and easy to read micrometer drum vernier scale that reads to 2 10 of a minute. The Mark 15 has a 7" (18 cm) frame radius graduated from 120 to 5 and comes with a traditional half silvered mirror. Comes with instruction booklet. Owner's Manual (pdf)