1 transmitter, 4 receivers, press the color-coded buttons to locate them, the beep sound and flashes will lead you to find the lost items, easy to use and operate.Transmitting range up to 30 meter: Radio frequency can penetrate through walls, floors, cushions, leather, etc to help find your item up to 30 meters away.Transmitter also has handy built-in LED Flashlight,which would be more helpful in darkness.ON/OFF button which located at the right side of the transmitter allows you to turn on or off the flashlight easily. This becomes extremely handy when you need to find something in the darkThe large buttons key finder specially fit for older people to use, the transmitter is removable from base and can be carried with you to find your lost items.