Sunbeam Little Sonic Egg Handheld Ultrasonic Bark Control Device, Gold

Do you have to change batteries frequently? My large one works but eats batteries.

The 'egg really worked for our dog. So we loaned it to a nextdoor neighbor who wanted to try it. Could it be reaching our dog?

Our neighbor dogs jump and growl at the fence when we take our dog out will this help?

How is this small device different than the full size one?