Shannon the center hole was 3/32 so they will fit a little loose. Someone on here found a little o-ring that made them fit tight the overall thickness was 1/16 of an inch. I found these at orchard hardware (OSH). I also found the gasket material there too which is twice the thickness of the original gasket but works fine as well. It’s all about making it work.
Melodica-Me
Monsters of Melodica