Made in the U.S. from premium aluminum that ensures even heat distribution for the best baking results. This muffin pan incorporates steel-reinforced rims to prevent warping. Each of the twelve cavities measures 2.5" in diameter to accommodate a standard paper baking cup. Lifetime warranty. To preserve the appearance, hand-washing is recommended; the dishwasher will cause discoloration that is cosmetic only, and will not affect performance.