This is a 12 steps 360 degree rotary encoder with clicking feel. This is different from potentiometer as it freely moves 360 degree without any limit clockwise or anticlockwise. The output of this encoder is gray code which gives its position and directional movement. The plastic shaft is 15 mm long and nice grove for knob.
Rotary encoders has many applications like audio volume control, motor position sensor to lots of industrial position sensing application.