Here are 5 Flip-over pot calls I shipped to the guy in PA along with the 12 3" pot calls I posted a few days ago. The top surface in all 5 is anodized aluminum and three of the calls have slate on the bottom and two have glass.
(http://genesturkeycalls.com/yahoo_site_admin1/assets/images/Flip-over_Pot_Calls.276103653_std.jpg)