JK TECH Rechargeable Dog Fence System Invisible Wired Pet Containment Fence System Waterproof Dog Training Collar for Small Medium Large Dogs Pulsed Proportional Stimulus:The closer your dog gets to the boundary, the more intense the shock will be;a warning tone will be issued first, then a shock stimulus if your dog continues to move closer to the boundary Variable Field Width Control:Allows you to precisely control the width of the signal field;the faster your dog is moving, the quicker the higher level of intensity is issued Audible and Visual Wire Break Indicators:Should your buried wire ever break, a loud sonic alarm will sound accompanied by a flashing light Built-in Lightning Protection:Protects transmitter from power surges caused by lightning strikes,Up to 5000 square metre range Multiple Collar Operation:Add as many collars as you like to contain as many animals you have. There is no limit to the number of collars it can control