Aetertek Heavy Duty Weatherproof Waterproof Version: 600 Yard Remote Dog Training Collar/Remote Dog Shock Collar Trainer for 1 Dog Remote dog training collar with 550 meters/600 Yards of range 100% waterproof dog collar receiver Rechargeable dog collar receiver; Adjustable shock plus one level of strong vibration and one level beep tone This one dog remote trainer can be upgraded to 2 or 3 dog remote trainer by adding extra 1 or 2 collars