Cookware Rolled-rim aluminium that will not warp at 450°F Three half-sheet pans, the tray every restaurant kitchen runs on. Flat, rigid, and the right size for a standard oven with room for air to move. Rolled rim A steel wire runs inside the edge. That is what stops the bang and the twist at high heat. Commercial aluminium Conducts faster than steel, so vegetables brown instead of sweating. Half-sheet standard 18 x 13 in fits the oven and every cooling rack and lid sold in that size. Stackable Flat enough to nest in a cupboard without a fight. 01 — The warp Why cheap trays buckle Thin aluminium with a folded edge expands unevenly and pops. The rolled rim with a wire core keeps the sheet rigid through a 450°F preheat. 02 — The colour Bare metal, not dark coating Dark nonstick trays absorb heat and burn the underside of cookies. Bare aluminium reflects, so the base browns at the same rate as the top. 03 — Three, not one Because you always need another Roast on one, rest on the second, and the third is in the dishwasher. A single tray is the reason dinner takes two rounds. The details Quantity 3 pans Size 18 x 13 in / 46 x 33 cm each Material Aluminium, 18 gauge Rim Rolled with encapsulated steel wire Oven safe Up to 500°F / 260°C Dishwasher Safe Warranty 2 years