Bakers Big Sheet natural aluminum commercial bakeware is made of pure aluminum which will never rust for a lifetime of durability;Baked goods rise and bake evenly due to aluminums superior heat conductivity and the reinforced encapsulated steel rim prevents warping;Pan exterior dimensions 21 x 15 x 1 inches and interior dimensions 19.5 x 13.63 x 1 inches;Easy clean up, hand wash only;Proudly made in the USA by Nordic Ware