Two-Pack Dog Fence Batteries for Invisible Fence Brand Receiver Collars by Perimeter Technologies Go to amazon.com Related posts 11 best perimeter collar battery for 2022 FeatureInvisible Fence brand Compatible.Works in R21, R22, R51, & Microlite Receivers.Less Expensive than the original.Guaranteed to work. DescriptionInvisible Fence brand Compatible.Works in R21, R22, R51, & Microlite Receivers.Less Expensive than the original.Guaranteed to work.