The military packaging authorities modified long-standing military specification MIL-B to MIL-PRF on April 30, 2001. The materials used and the specified method of manufacture remained the same, but the specification numbers changed.
For example, MIL-B-131 became MIL-PRF-131. If your drawings or contracts still reference the old MIL‑B numbers, the chart below shows the one‑to‑one correspondence so you can confidently select the correct MIL‑PRF material.
MIL‑B to MIL‑PRF Conversion Chart
Use the chart below to see how each legacy MIL‑B specification maps to its current MIL‑PRF designation. These conversions ensure you’re sourcing materials that meet today’s military performance requirements.
| MIL-PRF-121 Type I | Formerly MIL-B-121 Type I, Grade A, Class I |
| MIL-PRF-121 Type II | Formerly MIL-B-121 Type II, Grade A, Class 1 |
| MIL-PRF-131 Type I | Formerly MIL-B-131, Class I |
| MIL-PRF-131 Type I, Class II | Formerly MIL-B-131 Class II |
| MIL-PRF-131 Type I, Class III | Formerly MIL-B-131 Class III |
| MIL-PRF-22191 Type I | Formerly MIL-B-22191 Type I |
| MIL-PRF-22191 Type II | Formerly MIL-B-22191 Type II |
| MIL-PRF-81705 Type I | Formerly MIL-B-81705 Type I |
| MIL-PRF-81705 Type II | Formerly MIL-B-81705 Type II |
| MIL-PRF-17667 Type I Flat | Formerly MIL-P-17667 Ty. I , Cl. I Neutral wrap |
| MIL-PRF-17667 Type II Creped | Formerly MIL-P-17667 Ty. II Cl. I Neutral Wrap |
| MIL-P-130 Type I crate liner medium duty | |
| MIL-P-130 Type II Crate liner Heavy duty | |
| MIL-DTL-117 | Formerly MIL-B-117 |
We offer a range of mil spec materials that are certified to the specifications listed above. To see all the barrier materials we carry click here. Please note, specifications for materials are not the same as specifications for bags and tubing. All bags and tubing adhere to MIL-DTL specifications.
Understanding MIL‑PRF Specifications
The MIL‑PRF standards continue to govern watervaporproof, greaseproof, flexible and heat‑sealable barrier materials, just as their MIL‑B predecessors did. The only difference is the specification numbering.
Protective Packaging Corporation supplies a complete range of barrier materials certified to each MIL‑PRF type and class.
Note that material specifications (MIL‑PRF) are distinct from bag and tubing specifications, which fall under MIL‑DTL; all protective bags and tubing we manufacture meet MIL‑DTL requirements.
If you need assistance matching an old MIL‑B call‑out to a modern material or have questions about MIL‑DTL requirements, our team of packaging experts is ready to help.
FAQs
Why were the MIL‑B specifications changed to MIL‑PRF?
The Department of Defense consolidated and modernised its barrier‑material standards in 2001. While the numbering changed, the performance requirements and approved materials remained the same, ensuring continuity for military and aerospace applications.
Do I need to change my existing packaging materials?
If your current packaging meets the old MIL‑B requirements, it will still meet the corresponding MIL‑PRF requirements. The conversion chart confirms the direct correlation between the old and new designations.
How do I choose the correct MIL‑PRF type or class?
Each MIL‑PRF type and class corresponds to a specific barrier material with defined physical properties and use cases. Refer to
the conversion chart for the correct designation, and consult our product pages or call our specialists for guidance on selecting the right material for your application.
What is the difference between MIL‑PRF and MIL‑DTL?
MIL‑PRF specifications apply to the barrier materials themselves, films, laminates and foils, while MIL‑DTL covers the finished formats such as bags and tubing. Protective Packaging manufactures both MIL‑PRF‑certified materials and MIL‑DTL‑compliant bags and tubing to ensure full compliance in your packaging system.
Where can I source MIL‑PRF barrier materials?
Protective Packaging Corporation carries a full selection of MIL‑PRF‑certified materials, including MIL‑PRF‑121, MIL‑PRF‑131, MIL‑PRF‑81705 and more. We also offer custom converting into bags, tubing or sheets. Contact us to discuss your requirements and obtain a quote.
Protective Packaging: Your Partner in MIL-PRF Compliance
The shift from MIL-B to MIL-PRF designations may have changed the numbers, but it did not change the performance, durability, or reliability of the barrier materials trusted across military, aerospace, and industrial applications. By using the conversion chart above, you can quickly match legacy specifications to their current MIL-PRF counterparts and ensure full compliance with today’s standards.
Protective Packaging Corporation is committed to helping you navigate these specifications with confidence. Whether you need standard roll stock, custom-converted
bags, tubing, or sheets, our team is ready to provide certified materials, expert guidance, and responsive support. Contact us today to discuss your needs and secure the right MIL-PRF packaging solution for your mission-critical equipment.