The Silent Call Good Vibrations Receiver W/Battery Charger “Kit” is a battery-operated unit which receives signals from any 318MHz Silent Call transmitter which in turn causes a vibration and turns on an indicator light below the symbol to let you know which transmitter is sending the signal. Easy to wear on the waistband of slacks or skirts. Range up to 200 feet. Rechargeable 9-volt battery and battery charger are included to increase battery life. A fully charged battery provides around 35 hours of continual use. One year warranty on battery charger.