This Heavy Duty Containment System from SportDOG has been around for awhile and it is the only containment system from SportDOG and that is because it works, really well. It also allows for enough variation that any dog over 10lbs will be responsive to the system to where your pet(s) will be happily contained. Boundary flags for this system should be used for training and then very spread out and if possible left there so you don’t have to teach your dog the limits of the entire boundary system at once. By leaving them up in the future when your dog comes across them it will already know their meaning and will be able to avoid any stimulation. With an extremely durable and waterproof collar this system will be fully functional for a very long time and because it takes a 9 volt battery finding replacements is an easy inexpensive task.