This 6 volt premium lithium battery is specifically suited for use in Pet Stop, Perimeter and Extreme Dog Fence collars or receivers. This battery functions in the Pet Stop Ultra Elite, Ultra Elite Series 2, along with the Pet Stop Ultra Tuff. This Pet Stop dog collar battery is also compatible with the Perimeter Technologies containment system collar and Perimeter replacement receiver for the Invisible Fence systems. This battery comes conveniently packaged as one count blister pack card to make storing (and finding) them later should you choose to buy more than one at at time. Please store in a cool, dry location. Make sure that the battery is installed with the Positive + side facing outwards towards the metal battery cap, and the negative - side facing into the collar and touching the spring.