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Zeta III™ Helmet Liner for the HGU-56P


Oregon Aero Zeta III Helmet Liners
The Zeta III has been approved for use in HGU-56P helmets by PM Air Warrior.

The Zeta III Helmet Liner for the HGU-56P was designed for maximum comfort, protection, and helmet stability. Self-wicking outer fabric dissipates perspiration keeping your head cooler and drier. The Zeta III is easy to fit, install, maintain, and is equally effective while wearing Night Vision or other externally mounted equipment. The Zeta III has an upgraded foam core and offers the same level of comfort and performance as the original ZetaLiner® Helmet Liner.

Choosing the Right Zeta III Liner for your Helmet


The Zeta III is available in 3 different thicknesses for each helmet size. The thickness you need is determined by the number of layers in your existing Thermoplastic(TPL®) Liner.

NOTE: If your TPL(Thermo Plastic Liner) has been heated and fitted, you will probably need a Zeta III Helmet Liner one thickness thinner than listed below.

Find your Zeta III Liner Thickness

If your TPL® Liner Has... ...Then try a
2-3 Layers 3/8" Liner
4-5 Layers 1/2" Liner
5+ Layers 5/8" Liner

Once you have determined the thickness you need, choose the Zeta III Helmet Liner that matches your helmet size in the size tables below.

The sizing charts are intended to suggest a starting point for the fitting process. Each individual should be fitted for best comfort and stability. Oregon Aero is committed to helping you select the proper Zeta III Helmet Liner for your helmet. If you have any questions call us at 800-888-6910.

Zeta III Size Tables for the HGU-56P(Click the part # to order)

For Extra-Extra-Small(XXS) Helmets
3/8" Thick #9A-0043-102 NSN: 8415-01-671-3685
1/2" Thick #9A-0043-103 NSN: 8415-01-671-3705
5/8" Thick #9A-0043-104 NSN: 8415-01-671-3706
For Extra-Small/Small(XS/S) Helmets
3/8" Thick #9A-0038-102 NSN: 8415-01-671-3711
1/2" Thick #9A-0038-103 NSN: 8415-01-671-3713
5/8" Thick #9A-0038-104 NSN: 8415-01-671-3715
For Medium(M) Helmets
3/8" Thick #9A-0039-102 NSN: 8415-01-671-3740
1/2" Thick #9A-0039-103 NSN: 8415-01-671-3742
5/8" Thick #9A-0039-104 NSN: 8415-01-671-3744
For Large(L) Helmets
3/8" Thick #9A-0040-102 NSN: 8415-01-671-3758
1/2" Thick #9A-0040-103 NSN: 8415-01-671-3761
5/8" Thick #9A-0040-104 NSN: 8415-01-671-3768
For Extra-Large(XL) Helmets
3/8" Thick #9A-0041-102 NSN: 8415-01-671-3772
1/2" Thick #9A-0041-103 NSN: 8415-01-671-3779
5/8" Thick #9A-0041-104 NSN: 8415-01-671-3781
Oregon Aero Zeta-III Installation
The Oregon Aero® Zeta III® Helmet Liner being installed in a Military HGU-56P Aviation Helmet.

Easy Installation and Care


Your Oregon Aero Zeta III Helmet Liner is installed in 4 easy steps using hook/loop fastener strips. Complete instructions are included with the liner. If you would like to see how easy the Zeta III Helmet Liner is to install you can Click here to download installation instructions in PDF format.

Cleaning Instructions: Hand wash your Zeta III with mild soap and rinse thoroughly. To dry, place your helmet liner flat on a large towel. Fold the towel over to cover liner. Use a rolling pin or similar object to squeegee out the excess water. Do not wring liner. Re-Shape your helmet liner and allow it to air dry in a warm place or in front of a fan. Do Not Use Any Artificial Heat Source to Dry. Unless conditions are humid, your liner should dry overnight.

Note: Wringing your Zeta III or drying it with an artifical heat source will damage the liner. Use recommended methods of care only.