Here's what Karen has to say:
After many requests and much research I am finally able to bring you larger sizes of Perfect Circles®. There are ten different sizes ranging from 2-1/4” to 4-1/2” and they are made from heat resistant plastic so you can use them with an iron. These bigger sizes are great for the center of a Mariner’s Compass block, Drunkard’s Patch blocks, traditional appliqué and so much more.