I bought these pans to make cookies for my staff over the holidays. The pans went in and out of the oven for 24 hours over the course of two days, making multiple batches of five kinds of cookies at various temperatures. I used parchment paper and didn't take the pans over 350, so they still look unused... even the sticker I had overlooked on the bottom was in reasonably good shape. :)Per other reviews, mine had the "bad" stock number, but I have nothing but good things to say about these pans.