Dogtra SureStim H is fully expandable to a two-dog unit and feature a pager in the handheld transmitter, acknowledging that you have fully engaged the transmitter buttons.Ideal for stubborn dogs. Features:For small/medium dogs 20 lbs and upExpand up to 2 dogs.SureStim positive vibration feature in transmitterPrecise stimulation level (0-127)Low high output receiver for stubborn dogs1/2 mile rangeStimulation types in Nick, Constant, and a non-stimulating Pager vibrationInterchangeable Rheostat intensity dial or Selector "Step" dial stimulationStimulation types in Nick, Constant, and a non-stimulating Pager vibration modeRechargeable Ni-MH batteriesFully waterproof transmitter and receiver/collarLCD screen displays exact level of stimulation even in dark or low light conditionsThree bar battery life LED indicatorUser expandable to a two-dog system System includes:TransmitterBlack CollarReceiverBattery charger and splitter cableBelt clipOwner"s manual