Comfort-Fit Deluxe Little Dog Extra Receiver Collaris for use only with PetSafe In-Ground Fences. An unlimited number of pets can be added to the system as long as they are wearing a PetSafe In-Ground Fence Receiver Collar. Comfort-Fit Deluxe Little Dog Extra Receiver Collar is the perfect accessory for pet training.Our smallest waterproof receiver collarReceiver correction 4 levels plus tone onlyQuickFit? buckle provides quick release and perfect fit every timeFlexible collarLow Battery IndicatorLifetime Limited WarrantyAdjustable collar for neck sizes 6" to 26"Click here to download operating and training guide in pdf format.