Most Gap Pads have a Layer Material, or carrier substrate, option. In some cases there must be a standard Layer Material. This table makes the distinction between the five possible Layer Material options: Fiberglass reinforcement layer, Aluminum Carrier with a PSA, Polyethylenenapthalate (or “PEN”) Film, thermally enhanced Polyimide Film, and the ‘No Layer’ at all option. The Layer Material part number CODE is given in the table: “A” for aluminum, “G” for fiberglass, “PN” and “KT” for the insulator films. Whether this code is a prefix or a suffix onto the material name depends on the material itself. See the Therm-A-Gap™ data sheets for part number format details. The most common Layer Material is the fiberglass “G” reinforcement. This option lets the customer re-use the pad if necessary and allows for easy prototyping. The aluminum carrier option is the next most common Layer Material, where a peel and stick option is desired. The two film options are used for clean rework, enhanced electrical insulation, or low friction for easy positioning. The “No Layer Material option” is available for the 579 material within 0.120” to 0.200” thick.