The PetSafe PIG00-10674 Deluxe Comfort Fit In-Ground Radio Fence is the best pet containment system ever built by the world's best selling pet containment system manufacturer. It features a 25 acre transmitter with AC power supply, a lightweight programmable 4 level plus beep only mode receiver collar, built in lightning protection, 500 feet of 20 gauge wire (covers 1/4 acre), 50 boundary flags, a collar testing tool, installation manual and a training DVD. You can purchase additional wires and flags to expand your coverage area to up to 25 acres. You can put as many dogs as you like on one system as long as they are each wearing a receiver collar. Each kit includes one waterproof collar. All In-Ground Receiver Collars work with any In-Ground System or the Indoor Radio Fence. An unlimited number of pets can be added to PetSafe In-Ground Systems as long as they are wearing a compatible Receiver Collar. The new QuickFit buckle allows you to put the collar on or remove it in a matter of seconds. It also provides a perfect fit every time for added comfort. PetSafe PIG00-10674 Deluxe Comfort Fit In-Ground Radio Fence features: PetSafe 25 Acre Transmitter with AC Power Supply Built in lightning protection with replaceable fuses 100% Waterproof Receiver Collar programmable 4 level plus beep only mode receiver collar Audible Wire Break Alarm built into the Transmitter for 24/7 Protection Correction Zone Width Control Knob, Adjustable from 3' to 20' in width 500 Feet of 20 gauge Factory packed Underground Boundary Wire Containment Fence will cover approximately 1/4 acres of land 50 Training Flags included Installation Manual and Training DVD Collar Testing Tool Initial RFA-67 Battery Included (6 to 8 month battery life) Asics Microchip Chip, Over 3000 filters to prevent unwanted correction. Limited lifetime warranty Receiver collar features: Four adjustable correction levels plus beep-only mode to fit any dog's personality Receiver aprox. 2 1/2" x 1 1/4" x 1 1/2" weight only 2 oz Audible Warning Before Correction Stimulus. QuickFit buckle allows for a quick release and a perfect fit every time Safety Shut Off, Shuts your system off if your pet is in it for 20 seconds Rising Stimulus, If your dog does not back up from challenging the fence the stimulus will rise automatically Low battery indicator light, will let you know if your batteries need replacing Asic Microchip Chip, A chip the size of a match head with 3000 filters to prevent unwanted corrections