This is a student sextant, really only good for sun sights. It lacks a micrometer, so the only way of gauging minutes of arc is the vernier scale (less accurate than the micrometer).
It also lacks a clamp for the arc, so the arm can be jogged and the reading lost. In practice this is important because it means you can’t risk taking the sextant, unread, to the chart table, where you do the stopwatch & chronometer readings before reading the sextant.
The absence of a telescope doesn’t matter for sun sights, but for star sights you should definitely look elsewhere. I find the limited number of shades a disadvantage, too.
The Davis Mk3 is a student sextant and can only really be used for sun sights Price £69.95 Weight 198g Arc radius 180mm Telescope None Shades 2 full-width, 2 index Contact Davis Instruments Web www.davisnet.com Tel +1 (510) 732-9229