This is a pack of two Nhilvyg Smart Bark Collars, perfect for training your dog. The collars are suitable for all dog breeds, in sizes small, medium, and large. They use vibration and static/shock control methods to help your dog learn to bark only when necessary. The collars are waterproof and come with a low battery indicator, so you can be sure they'll last through every adventure. They also have adjustable shock levels and are rechargeable, making them a convenient choice for pet owners. These collars are perfect for anyone looking to train their dog to bark less, or to simply help their furry friend communicate more effectively This one is missing instructions but there are a lot of how to videos on how to use these.