In the full-featured Mark 25 sextant, the conventional half-silvered mirror has been replaced with a full field Beam Converger mirror, sometimes referred to as a full-horizon mirror, which combines horizon and astrobody images in a single field for easy, reliable sights. A special coating is applied to high quality optical glass to allow the user to see through this mirror, yet still pick up images as faint as low-light stars
Special mineral coating is selective for different wavelengths of light - horizon is transmitted in one color and the star or sun in another
Precision machined slow travel worm gear
Readings to within 12 seconds of arc
Seven sunshades
Light weight and corrosion proof, the Mark 25 is made of an upgraded plastic that is very stable
Arc and drum are illuminated by a long-life LED
Comes with instruction booklet and padded, shock-resistant carrying case