The standard hive nail is a 7D box nail and they're available from suppliers here in the U.S. If you can't find those then the 6D hot dipped galvanized nails work just fine. The good thing with box nails is that they're smaller diameter than common nails and don't split the wood as often. I bought a bunch of old supers from another beek last year and was filling them with frames yesterday; found a bunch of them that were nailed with 12D commons, then stapled later, then renailed with 8D nails. The bees just really don't give a hoot! They seem to like whatever you give them as long as it's warm and dry.