Limit switches react to physical contact to detect whether objects are present, absent, or at their preset destination. As objects pass the limit switch, they make contact with its actuator, which is mechanically linked to the electrical switch and turns the circuit on or off. Limit switches are sealed to protect their internal components and provide reliable operation in harsh or hazardous locations. Roller- and rod-lever-arm limit switches move in circular motions to actuate. Plunger limit switches actuate from downward force. Roller-plunger limit switches spin to actuate. Wobble-stick limit switches track omnidirectional movements. Limit switches without actuators are head and body modules. Operators for limit switches are actuators that interact with moving objects. Bodies and receptacles for limit switches are the backends of limit switches that house and connect wiring. Heads for limit switches are the front ends of limit switches that secure actuators.