Perimeter Technologies Invisible Fence Compatible R21 R51 Batteries - 12 pack

How far out is the expiration date on the battery package?

How can you tell what type of power cap to get? I do not see a R21 or R51 on the Invisible Fence Power Cap

Why can I not place a re-occurring order for these batteries?

the only marking on the IF collar we have is pn #900-0025-01. Compatible?