Ofeneinlage, antihaftbeschichtet, strapazierfähig, hitzebeständig, Fiberglasmatte, wiederverwendbar, Silikon, extra dick, 100% PFOA und BPA-frei, leicht zu reinigen, Gas, Toaster und Mikrowellen

Q: Where do you place the liner, underneath the the element in the electric oven?

Yes,If you have a heating element on the bottom of the oven, you can lift it and put the liner under it. The newer ovens have no obvious heating element (its underneath the floor of the oven so in that instance put it on the shelf at the lowest position in the oven. They work great to keep ovens clean,i really like these liners! Hope that helps you.

Q: can liners be left in toaster oven between use?

I don't know if I would. I cut mine to use in my toaster oven, on the bottom as you would in an oven, and left it in just for four different times - we heated egg rolls,vtwice, on a cookie sheet, and made toast, also on a cookie sheet. I took it out to wipe it off after the fourth time, and there was a nice 2-in circumference white spot that was ash and when I rinsed it there was also a ¼" hole. I don't guess there's a way to post a picture here for you or I would because I have several photos. I won't be buying these again.

Q: Can this be placed directly on the gas oven floor?

As long as it doesn't cover any heat vent holes if you have a gas range. It can be easily cut to fit any configuration on your oven bottom.

Q: Is this okay for the bottom of a gas oven? I have double ovens and thetop one has only one rack.

Yes, I have a gas oven and the liners work just fine. I love them because they are so easy to clean! You can cut the liner to the right size to fit your oven. Enjoy!