Rotary switches move in a circle and can stop in several positions. There are two basic styles: single-deck and multi-deck. Both types of rotary switches can be actuated with a bare or knobbed shaft, a flush actuator, or a key. Angle between positions, mechanical life, number of poles, number of decks, and number of poles per deck are important physical switch specifications to consider. Measured in degrees, the angular distance between positions determines the number of switch positions. For example, a 4-position rotary switch has a 90° angle of throw. For a 100-position rotary switch, the angle of throw is 3.6° degrees. Mechanical life represents the maximum life expectancy for rotary switches. The number of poles is the number of separate circuits that can be activated at any given time. The number of decks is the maximum number of decks that can be attached to a common, actuated shaft. The number of poles per deck is the number of separate circuits that can be activated through a rotary switch per deck.