*** Please contact us for current availability in our stores before ordering. Other sextant models are also available upon request.***DO NOT KEEP IN DIRECT SUNLIGHT OR NEAR A STRONG HEAT SOURCE TO AVOID PLASTIC EXPANDING OR WARPINGDavis plastic sextants have emerged as truly viable instruments for celestial navigation. Their accuracy is not as great as with metal sextants, & their errors vary with temperature, making frequent IC checks advisable. They make acceptable “first” sextants if finances are a constraint, & are always useful as back-up sextants. The MK 25 is gray in color, built of a more stable plastic which is resistant to temperature changes. MK 25 has illumination & a whole horizon mirror & comes with an instruction booklet, plastic carrying case, neck lanyard, 3x scope & a sight tube. Arc: -5° to + 120°, radius 178mm Accuracy: Unpredictable Micrometer: 1` scale, vernier 0.2` Mirrors: 50×38 mm index, 42×29 mm horizon Shades: 4 index, 3 horizon Weight: 15 oz.