Electric rotary actuators drive components rotationally via electromagnetic power from a motor. They typically provide control and indexing capabilities to allow multiple position stops along strokes. The rotational element for electric rotary actuators can be either a circular shaft or a table. Circular shafts often include keyways while tables provide a bolt pattern for mounting other components. Both single and double shafts are available. Important dimensions include shaft or table diameter and shaft length or table height. The length of the shaft is measured from the body of the actuator. The table height or thickness does not include the actuator body. With some electric rotary actuators, the angle can be adjusted via screws or other stop adjustments. With other devices, the angle can be adjusted on both ends of the angular stroke. Special features include cushioning to soften stops, position feedback devices such as encoders and potentiometers, and magnetic bands that can be read by a switch.