The Dogtra EDGE is a fully customizable and expandable, up to a 4-dog system, e-collar, designed for professionals and serious amateurs. It features a 1-mile range, 2-hour rapid charge batteries, fully waterproof Receiver and Transmitter, and built-in high intensity LED location lights on the Receiver. Package Contents: TransmitterReceiver/Collar (1) Additional Receivers sold separatelyBattery charger and splitter cableTest lightOwner's manualExchangeable selector dialContact point extensions (2) and adjustment toolMetal belt clip and screws (2)Carrying caseFeatures: Interchangeable Rehostat intensity dial or Selector "Step" dial stimulationStiumulation types in Nick, Constant, and a non-stimulating Pager vibration modeBuilt in high intensity LED lights on the receiver/collar2-hour rapid charge Lithium-Polymer batteriesFully waterproof transmitter and receiver/collar1 mile rangeExpandable to a two, three, or four-dog systemInterchangeable contact points for a variety of coat lengthsOther Details Warranty - Platinum 2-year Warranty, Limited Lifetime Warranty (after 2 years)Power - Low to HighRange - 1 MileBatteries - Lithium PolymerLCD Screen - YesCarrying Case - YesExpandable - Yes, up to 3 additional receiversPager Mode (Vibration) - Yes