Ultralight Sonic Bark Control CollarThe biggest barkers are usually the smallest dogs. Now there is a bark collar designed for even the smallest little yipper. The new PetSafe UltraLight Sonic Bark Collar weighs only one ounce, so it can be worn by any size dog. It snaps right on to your pets existing collar so it doesn't have to wear a second collar. It's adjustable sensitivity levels allows you to customize it for your dogs unique bark. To deter barking, it emits a loud sound that startles your dog, disrupting its barking and discouraging it from continuing. While very effective, it is perfectly harmless.