The MB-1 is a versatile battery-operated mobile boundary that can be used either indoors or outdoors to create a pet-free zone. It is waterproof for outdoor use and it has a rechargeable battery. It is wireless (used without a boundary wire), so it is easy to set up wherever you need it. The MB-1 creates a pet-free zone up to 8 feet in diameter (4 feet from the center). If you want a portable boundary that can be used anywhere to protect a small area (trash, counters, furniture, flower gardens, sandbox, etc.), this is a perfect choice. Includes MB-1 transmitter, battery charger, and four indoor training flags. Receiver collars must be purchased separately. Works with all DogWatch FM receivers.