Safety 1 Dog Hidden Training System Pet Electric Underground Yard Fence Collar Pulsed Proportional Stimulus--The closer your dog gets to the boundary, the more intense the shock will be. Progressive Tone Stimulus--A warning tone will be issued first, then a shock stimulus if your dog continues to move closer to the boundary. Variable Field Width ControlAllow you to precisely control the width of the signal field. Audible and Visual Wire Break Indicators--Should your buried wire ever break, a loud sonic alarm will sound accompanied by a flashing light. Speed Detect Anti-Run through--The faster your dog is moving, the quicker and higher level of intensity is issued.