If there is some police activity close to you like a vehicle accident or emergency situation and you are not picking up anything on your scanner, switch on signal stalker and it will lock on to any frequency being used in the immediate area. Or if you were outside a walmart or other large store/warehouse and would like to know what frequency they are using switch on signal stalker and it will pick it right up as soon as someone keys up the radio. It is only good for short distances, maybe 1/4 mile. It's a very neat little trick feature and can come in very handy. Mine scanns the entire frequency band very quickly.