High Tech Pet BT-3 Bark Terminator 3 Multi-Mode Micro Bark Control Collar Three modes of bark or howl detection plus the ability to select shock or no-shock with each mode Microprocessor monitors the barking pattern and is able to tell the difference between the bark of a dog and stray sounds in the environment Water resistant, rain and snow will not affect operation Weighs only 2 ounces; recommended for dogs over 5 pounds