Aetertek AT-215 600 Yard Remote 2 Dog Pet System Vibration Electric Shock Training Collar Used as 1 dog or 2 dogs remote dog training collar system (This list is for 2 dogs with 2 receivers ) Strong shock + weak shock + strong vibration to get your dog's attention Solid remote working range up to 600 yards (550m) and signal can pass through walls and fences Pls keep the receiver charge port closed for dust, moisture prevention Rechargeable and water-resistant(not waterproof) receiver collar, pls DO NOT make your dog swim with the receiver collar