It's a law of nature - "cherry pies shall overflow in the oven." But slip this non-stick, steel oven spill guard under pans and casseroles and the overflow is neatly caught. No mess or oven cleanup. The oven liner's raised center gives even heat flow. 12 1/4" diameter. Inner opening 6 7/8" diameter. Non stick oven liner fits pie pans 8" diameter and larger. Dishwasher safe.