“Motion” is the term used to refer to how many different components a radio can control. A 1 motion radio is used to control a hoist. A 2 motion radio is used to control a hoist and trolley. A 3 motion radio is used to control a hoist, trolley, and a bridge. Radios with 4 or more motions are for more advanced applications where the operator wants control multiple hoists, trolleys, or bridges all at the same time.