Thermotec Aluminized Heat Barrier is designed to either protect components from heat, or hold heat inside a component. Capable of withstanding radiant heat temperatures of over 2000 degrees f and direct (touching) temperatures of over 750 degrees f. It is made of woven silican with a flexible aluminized finish. For conductive applications, the fabric side can handle temperatures of up to 1200 degrees f.
The part number for this item is 14051 and it is a 36" by 20" piece that can be easily cut with a razor knife.