This extra Receiver Collar can be used to add another dog or as a replacement collar to the Wireless Pet Containment System (PIF-300-21). This collar is not a complete system and needs to be used with a compatible transmitter. Over Stimulation Protection: Stimulation stops after 30 seconds Collar uses 1 x 6 Volt battery (included) Battery usually lasts 1-3 months Fits neck sizes 15 - 71 cm Compatible with the Stay + Play Wireless Fence™ or Wireless Pet Containment System Waterproof