PetSafe Stubborn Dog Pro Grade In-Ground Dog Fence - 1/4 Acre Up to 10 Acres (1-5 Dog Kits) Features: 2 PetSafe Stubborn Dog Collars (with Standard Contacts and 9v Battery), PetSafe's Stubborn Dog Transmitter, Surge Protector, 2000' of eXtreme Brand 14 Gauge Boundary Wire, 50' of eXtreme Brand 16 Gauge Twisted Wire, 8 Waterproof Wire Splice Kits, 10 Landscape Staples, 200 Boundary Flags, Test Light Tool, and Instruction Manual Your eXtreme 14 Gauge Wire will Be Shipped in A Continuous Spool Up to 3000' (Which Covers 10 Acres, the Maximum Coverage that the PetSafe Stubborn Dog Can Contain). That Way, You Won't Have to Splice Multiple Spools of Boundary Wire Together When Running Your Perimeter. PetSafe's Stubborn Dog Fence (In Particular, the Collar) is Designed for Dogs that Are Over 50 Pounds. This System is A Great Solution for the Guardian and Sport Breeds, as Well as General Medium-Large Dogs that Have A High Energy Personality and/or A High Threshold for Discomfort. The Collar Will be Too Bulky for Smaller Dogs. It is Powered by A Standard 9 Volt Battery, Which Makes it One of the Easiest Collar Batteries to Replace, When it Runs Low. This Collar is Also Completely Compatible with the PetSafe Indoor Pet Barrier Model #: PIRF-100 (Which Creates a Circular Boundary from 2' to 10', that will Prevent Your Pet from Jumping on Furniture, Entering an "Off-Limits" Room, etc.). In Addition, You Can Add Any of the Following PetSafe and SportDOG In-Ground Collars to the System with Full Compatibility: PetSafe Rechargeable Collar (PIG00-13737), PetSafe Elite Little Dog Collar (PIG00-10778), PetSafe Deluxe Ultralight Collar (PUL-275), PetSafe Cat Collar (PIG00-11006), SportDOG Collar (SDF-R) The Stubborn Dog Collar Has 5 Levels of Correction that is Set in Each Collar Individually. This way, Each Dog on the System Can Have A Collar Correction Strength Best Suited to His/Her Individual Personality. The Collar Also Has the Unique Feature of A Vibration Warning Coupled with the Audible Warning, for Dogs that Are Hard of Hearing. The PetSafe Stubborn Dog Fence System Can Accommodate Any Number of Dogs, with The Purchase of Additional Collars.