MIL-PRF-131K Class 3

flexible mil-prf-131k class 1 bags
heat-sealable mil spec bag
single milspec paper bag
openned moisture barrier bag


The MIL-PRF-131K is a durable, tear, and puncture-proof barrier against water vapors, air, and light. It's designed for military use to protect against moisture. This material is Class 3, which means it creates a strong barrier against water, vapor, and grease, in addition to being flexible and heat-sealable.

Our bags are converted in accordance with MIL-DTL-117 and follow the specifications and standards set forth by the U.S. Department of Defense.

Protection Properties

MIL-PRF-131K is a Class 3 material composed of four layers:

  1. Scrim
  2. PE
  3. Foil
  4. PE

Its durability comes from the buried metal construction that provides its Faraday Cage performance for protecting against static charges. It works by surrounding the product in the bag and dispersing electromagnetic and electric charges along the outside, so the product remains safe and free of interference.

The material is available in pouch form, tubing, and roll stock.

Material Uses

The MIL-PRF-131K CLASS 3 barrier material is designed for applications that need protection against moisture from water and vapors. It is commonly used in the military to preserve items against damaging elements. Because common one application is to protect military engines by enclosing the item entirely before crating, they are sometimes referred to as engine bags.

Its features also make it an excellent solution for the Navy and naval aviation equipment. Given the nature of the work environments, equipment used in these applications is exposed to high concentrations of moisture and salt as well as rough handling, transfer at sea, and poor storage conditions. There are no similar barrier materials available that meet these rugged demands for the Navy, which speaks to the strength of MIL-PRF-131K CLASS 3.

Become a Caltex Distributor

MIL-PRF-131K CLASS 3 barrier material is one of the best on the market for moisture protection. Buy MIL-PRF-131K CLASS 3 packaging to supply your customers with the protective barrier materials they need for their military and electronics equipment. Send us a message on our website to request more information about becoming a distributor.

Find MIL-PRF-131K Class 3 Packaging for Sale Online From Caltex

Caltex is a leading provider in materials for specialized storage solutions for the military. We manufacture our packaging products to meet all MIL-SPEC regulations. With our packaging materials, you are getting a top-quality product at a cost-effective price. Since 1984, we have been the trusted source for MIL-PRF-131K CLASS 3 packaging and more.

Whatever your packaging need is, we have the right material for you. To learn more about MIL-PRF-131K CLASS 3 packaging and our other products, contact us today.


- Ideal for packaging of PCB's and IC's
- Extremely durable buried metal construction give Faraday Cage performance needed to shield against static charges.
- Available with zipper closures.
- Contains no amines or amides, is N-Octanoic acid free and is polycarbonate compatible.
- Custom printing and thermal transfer are available.
- Side gussett, bottom gussett, and T-Seal bag configurations.


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made in the usa aib international certified defense standardization program fda approved

Last updated: April 28th, 2020

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