The ones with the double bottoms with an air space in between.

I have an insulated jelly roll pan which I used for the first time
last night. As it turns out, I have to pay attention to the size
called for in recipes because mine is just a tad bigger than what's
callef for, and that makes a difference.

Last night I used it just like I would a normal pan (put in the middle
of the oven) but noticed there wasn't much oven spring and the cake
texture was bad (I tossed the whole thing). Part of that could be due
to the mixing directions not being adequate (I used the recipe exactly
as written). But I reasoned also that the bottom might take too long
to heat.

So this morning I tried again. I made some changes in the recipe and
the mixing process. I put the cake on the *bottom* rack, closest to
the heat source.

Much better!

The problem I have with insulated cookie sheets is the cookie bottoms
don't brown.

At least I don't have to buy a new jelly roll pan.

Sue(tm)
Lead me not into temptation... I can find it myself!