MIL-P-997D, MILITARY SPECIFICATION, PLASTIC MATERIAL, LAMINATED, THERMOSETTING, ELECTRICAL INSULATION: SHEETS, GLASS CLOTH, SILICONE RESIN (23 NOV 1966) [S/S BY MIL-I-24768/17]., This specification covers type GSG, class 180 plastic insulating material having fire and electrical arc resistance, heat resistance, and very good electrical insulation resistance and dielectric loss characterics.