They are made from aluminum that has gone through a treatment process that makes them very durable and somewhat nonstick.
Baking sheets not aluminum.
Also some manufacturers coat their aluminum cookie sheets with substances much worse than aluminum including toxic non stick chemicals which is often done to improve the cooking performance of the stainless steel cookie sheet.
Our favorite rimmed baking sheet is made out of aluminum and perfectly safe to use but avoid cooking acidic foods on it.
Our favorite traditional skillet is clad in a non reactive material stainless steel that surrounds an aluminum core for even heating.
Stoneware baking sheets personally i ve not used stoneware bakeware.
The parchment paper can be used in ovens up to 425 degrees.
The other problem with stainless steel is that it really is not the best option for conducting heat uniformly and consequently your cookie recipes might not turn out the way you expect.
Cover non coated aluminum baking sheets with unbleached parchment paper so you food isn t touching the aluminum.