The only type of coin holder that's labeled explicitly for Philharmonic is this: http://www.collectons.com/shop/item...or-37mm-Coins-1-Oz-Austrian-Philharmonic-Gold But after I actually tried it, I found it is not really "air tight", because the coin is still somewhat at loose when you have presumably sealed it in the capsule. This prompted me to look for better alternatives. I'd appreciate people's recommendation based on your actual experience. Thanks!
Buy the airtite "I" series at 37mm but with the black ring insert. That will stop the coin from moving around inside. There is just a plain edge on the bullion so you don't cover up anything.