Add unlimited pets to your system Keep as many pets as you need safely in your garden with this add-a-dog receiver collar. Compatible with all PetSafe In-Ground Systems except YardMax® and UltraSmart®.4 levels of stimulation Plus tone-only mode for training. Pets can be trained in 2 weeks when used as directedWaterproof receiver collar With low battery indicatorAdjustable receiver collar Fits pets 3.6 kg or more with neck sizes of 15.2 to 66 centimetres