Insulating fabric? Help me find?

I'm hoping to make some pot holders for my mil for Christmas (I know it's early but it's gonna take me a while to sort out / make)

Where can I find the insulating foam/ fabric for in the middle?
Does it have a particular name?

Thanks ladies!

I've made a few oven gloves. I use Insul-Brite for the insulated layer and warm & natural for the quilting layer. I also use denim for the inner of the glove, then a cotton outer. You might want to invest in a denim needle for your sewing machine. Can't help with where to buy ...

i thought you had said insulting fabric !