The Cookie & Baking Sheets by Chicago Metallic: Stayflat Sheet Pan, 17-7/8 x 25-13/16 x 1 overall, wire in rim, 18 gauge aluminum, plain ( Chicago Metallic - 40804 ) - Constructed of 18-gauge aluminum, the Chicago Metallic 40804 sheet pan offers conductive durability-great for baking cookies, rolls, and other goods. Its full-size body measures 2513/16 inches long by 177/8 inches wide by 1 inch high and features StayFlat technology that keeps its bottom from bowing in the high heat. Its sports a plain-coated exterior and has a band-in rim to ensure simple transfer from countertop to oven Product Details. StayFlat pan. Made of 18-ga. aluminum. Rim contains wire support. Plain adornment. Overall dimensions: 2513/16 in. L x 177/8 in. W x 1 in. H. Product Features.