Invisicell Invisible Fence&reg; Brand Compatible Rechargeable Battery Invisicell - Invisible Fence Brand Compatible Rechargeable Battery Includes Rechargeable Battery Compatible with Invisicell and Circuitcell Charger Compatible with Invisible Fence R21, R22, R51 and Microlite Collars Lasts 30 days on Single Charge Environmentally Friendly / No Battery Plans / Low Cost - 80% Savings