After the initial training period at home, dogs quickly learn to respond to the warning tone prior to any static correction in new locations and with 15levels of stimulation to choose from, you can select the level that is right for your dog -- a gentle reminder or higher levels for difficult dogs or dangerous situations. The included remote trainer allows you to provide additional training to your dog using voice to dog collar, tone, vibration, or static correction. Contains up to 2 dogs (addition collars sold separately - TRAVELCOLLAR50). Wireless fence unit is a backlit LCD screen. Coverage up to 990ft when there is a clear line of site between wireless fence unit and collar unit. Range may vary depending on area ofinstallation of wireless fence unit indoors. Communicate to your pet with Push-to-Talk feature. 2 training modes: warning tone only, gentle vibration or 15levels of static correction.System includes: wireless fence unit with LCD scree, remote trainer unit with LCD screen, pet collar unit for pets over 20lbs, power adapters (for collar and fence units), rechargeable battery for fence unit, 2 AAA batteries for remote trainer unit, nylon collar strap, 2 sets of collar contacts, 50 training flags, test light, outdoor ground stakes and user's guide.