Dogtra Dog Fences allow your pet the freedom to explore a large area of up to 40 acres safely. Dogtra Dog Fences and Dogtra products are developed with the sporting dog in mind. Dogtra products are made to be tough, durable and have the ability to withstand the toughness out in the field with sporting dogs. Dogtra Dog Fences provide some great features such as wire continuity indicator that warns the owners of any disconnections, a digital signal that eliminates unnecessary interference from stray signals and the ability to add multiple dogs easily to the systems. One of the best features of dogtra dog fences is the automatic sleep mode. Your dogtra dog fence will "go to sleep" once your dog is away from the boundary which will save battery life not to mention money since you won't have to buy as many batteries.