Samsung SmartThings Arrival Sensor

Peace of Mind
Put the sensor in your child's backpack, or your dog's collar and be notified when he/she arrives home, or leaves the house.
Keep Track
Keep track of where you've placed your keys by triggering a beep based on the location of your sensor.
Trigger Actions
Trigger different actions to take place when you arrive or leave home, such as automatically turning the lights on or off.