You are correct, Greg. Keep in mind that the holders have been used in the coin industry for years:

38mm - Morgan Dollars
39mm - 1 Ounce Silver Rounds
40mm - Walking Liberty Silver Eagle

We just adapted these holders to work for our hobby. BTW, we also carry Airtites for all US Coins from Pennies to Dollars, including the 50 State Quarters that everyone is collecting.

Chris