PetSafe Stubborn Dog Add-A-Dog® Extra Receiver Collar. For dogs 3.6 kg and up. Fits neck sizes 15 - 71 cm. 5 adjustable levels of static stimulation. Tone with vibration mode alerts your pet with a beep. Over Stimulation Protection: Stimulation stops after 30 seconds. Covers up to 13 ares (1/3 acre/0.13 hectares) with included boundary wire. For stubborn or hard-to-train dogs. Uses 1 x 9 Volt battery (not included). Battery usually lasts 1-3 months. Compatible with PetSafe® In-Ground Fence systems. This extra Receiver Collar can be used to add another dog to any PetSafe® In-Ground ...