Servomotor. This is a rectangular motor with a round shaft protruding from one of the narrow sides. a wire connector protrudes from the diagonally opposite corner. The motor is approximately 1.t5 inches square (about 4cm) by half an inch thick (about 1cm). The shaft connects to one of several plastic horns so you can attach it to things you want to move. When turned by hand, the shaft will only turn 180 degrees.