Yard Barrier Outdoor Sonic Dog & Cat Fence YB-1 Uses sound, not shock, to keep pets out of flower beds and gardens, off porches, away from pools, ponds, trash cans or any other off-limits area Heavy duty waterproof outdoor receiver unit may be placed anywhere that's off-limits to pets Lightweight waterproof electronic collar sends an ultrasonic signal that triggers a loud audible sonic blast at the receiver when the pet approaches Allows people to come and go without triggering the alarm Requires one 9-volt alkaline battery (not included)