MIL-PRF-131J, PERFORMANCE SPECIFICATION: BARRIER MATERIALS, WATER VAPOR-PROOF, GREASE-PROOF, FLEXIBLE, HEAT-SEALABLE (26 AUG 1998)SUPERSEDING MIL-B-131H]., This specification covers the requirements for heat-sealable, greaseproof, flexible barrier materials having low water vapor transmission characteristics for use in military packaging.