The PetSafe 1/2 Acre Radius Wireless Pet Containment System is a great way to keep your PetSafe and secure in your yard. It allows the freedom to roam within a 1/2 acre radius. If your pet gets close to the coverage area limit a noise will sound to warn them, if they continue they will receive a mild static correction to encourage them to remain within the boundaries. • Receiver collar is sized for pets over 8 lb. • Centrally located transmitter sends an adjustable radio signal of up to a 90 foot radius (over 1/2 an acre) to a small, lightweight receiver on your pet's collar • Provides a safe zone for your pet that cannot be run through, dug-under or jumped over • 3 adjustable levels of correction and a bonus tone-only mode • One 6-Volt lithium battery required (sold separately) • Will support multiple dogs with additional PetSafe wireless receiver collars, model number IF-275 (sold separately) • You can double the coverage area by adding an additional transmitter model number IF-100 (sold separately) • Waterproof receiver