Melange Natural Aluminum Commercial Baker's Big Sheet and Half Sheet, Pack of 12 Pack contains twelve big and twelve half sheets. Big Sheet size: exterior - 21.5" x 15.5" x 1", interior - 20.5" x 14.5" x 1". Half Sheet size: exterior - 17.88" x 12.88" x 1.06", interior - 16.5" x 11.38" x 1" Made from heavy-duty warp resistant commercial-grade 18 gauge aluminum. This provides fast and even heating Professional grade with superior conductivity. Food bakes evenly and the sheet does not warp even with heavy loads Made from top rated scratch resistant rust proof 3003 Aluminum Tapered on edges with closed bead surround. FDA and NSF certified