In-Ground Radio Fence 18 Gauge Wire, by PetSafe

He'll hear a warning tone as he nears the boundary you've established and a quick correction if he attempts to cross it. The lightweight, adjustable collar is the perfect complement to the newfound freedom your dog will experience on his old turf.

Features:

Waterproof UltraLight™ receiver with adjustable collar

Includes 500 ft of 18g wire and 50 boundary flags (covers up to 1/3 of an acre)

Covers up to 10 acres (additional wire and flag kits required)

Works with multiple pets (additional receiver collars required)