Davis Mark 3 Marine Sextant 
Mark 3 Marine Sextant
Sometimes referred to as a "lifeboat" sextant, the Mark 3 is an inexpensive training sextant. Yet this model has taken sailors around the world, too! It is full-sized and has sunshades, but no optical magnification to help you find dim celestial bodies.
Comes with instruction booklet.
Owner's Manual (pdf)