PetSafe Wireless Pet Containment System One Dog System - Provides the safest, simplest form of pet containment - Plug in the transmitter emits a 17.5 kHz radio signal around your home - Lightweight receiver collar - Low and high boundary Switch - Boundary Control When your pup approaches the boundary of the signal area, they will receive a warning beep. If your dog does not return, they will receive a static correction which is startling but not harmful. With a little simple training, your dog will quickly learn their boundaries. The training of your pet is a key element with the Pet Safe Wireless Fence. Follow the easy instruction and training manual that is included. Pre-owned this set included components shown. Additional collars can be purchased separately through amazon