The 5" Brass Rack and Pinion Sextant has an adjustment knob that drives a pinion gear against machined teeth on the limb of the sextant to allow fine adjustment of the inclination angle. Both mirrors are fully adjustable and there are six swing-arm filters. The sextant measures 6.5" tall, 7" wide, 4" deep and weighs over 2 lbs. A built-in magnifier can be swung into position to assist in reading the German Silver vernier scale. The sextant's index arm is engraved "Stanley London 1878." On the back of the sextant is a large solid hardwood handle. The sextant comes with a solid hardwood case with a solid brass plaque engraved "Stanley London." The case has two front clasps and the corner joints are strengthened with beautiful inlayed hardwood splines. While these models are fully functional, they are not calibrated nor intended for navigation. They are perfect for the collector or anyone interested in learning celestial navigation.