Okay, this is a bit unusual, but I've been using this type of product for nearly 20 years and wouldn't be without it. What I'm posting is large sheets of what I have, but one could cut this product to fit any cooking/baking pan. I've done it.
The cookie sheets are the same ones I began keeping house with in 1968 and with the help of these Teflon sheets, they should last another 40+ years.
I also use them in my other baking/cake pans and have never found any fault with them.
I can't remember the company I purchased my Teflon sheets from, but these
are essentially the same thing. Just cut to shape.
Another "plus" with these sheets is that you can gently slip the sheets off your cookie sheet and onto a cooling rack, not damaging the cookies at all. Then, you can cool the cookie sheet in readiness for another batch of unbaked cookies. Slip the Teflon sheet back on, drop the cookies and have at it once again.