I believe my dealer gets absorbent glass mat (AGM) type sealed lead acid batteries. They come empty with a pack of acid stored separately. The cap strip is there to allow filling of the initial acid solution in the battery prior to first charge. That way, you get a fresh battery and not one that is stored activated for an unknown period of time before you get it. The strip isn't meant to be pried open after the initial fill for refilling though.
Sometimes the non-sealed lead acid batteries have a clear casing with marks on the side, so you know when to refill them.