ClayShield comes with 14 Panels that are each 4 1/8" wide and 8 3/4" tall. They form a 20" circle when placed together. Your actual working circle will be larger because you'll need to allow an opening for your hands to work while trimming. The actual diameter of the circle will also depend on the type of splash pan you have (if you need to cut two panels to tuck under a splash pan.) Typically, the set gives enough space for most potters.