SportDOG Brand In-Ground Fence Replacement Transmitter

Expands up to 100 acres with purchase of additional Wire & Flag Kits (SDF-WF) Expands to any number of dogs for containment with purchase of additional Collar Receivers Compatible with SportDOG In-Ground Fence System (SDF-100A), In-Ground Fence Add-A-Dog collar (SDF-R), SportDOG Brand Contain + Train System (SDF-CT) and Contain + Train Add-A-Dog collar (SDF-CTR)You may also like PetSafe Basic In-Ground Pet Fence – Covers 1/3-Acre Yard with Included Wire – Expands up to 5 Acres.