I have a 9 month old Golden and found this product to be less than reliable. Changing the area size of the zone was inconsistent and the only way my Golden reacted to the collar was by turning it up to max shock. This morning she saw a dog walking across the street and ran right through it without even a whimper.I did call the 800 for but I am returning this unit for a different one from a different manufacturer.UPDATED REVIEW JUNE 15,2018After purchasing the "stubborn dog collar"