This mutifunctional SECURE DOG alarm system uses an electronic radar-wave sense control. This technology allow it to “see” through wood, cement, brick, glass, etc. When an intruder comes within 22 feet, it automatically begins barking like an angry dog. From outside, it sounds like you have a very unfriendly dog inside. It has a 1200 field of view. The radar sensitivity and volume control are adjustable. Stands 9 inches tall. It also can announce visitors with a melody of birds, frogs and waterfall sounds. These relaxing sounds can also be played whenever you want a soothing background sound. AC power supply.