Zeta II Overview/Sizing
Step 1: Choosing Your Zeta II® Helmet Liner Length
Use this guide and the tables below to determine which size Zeta II® Helmet Liner is right for you. Measure the inside of your HGU-56P helmet from front to back — down through the bowl — as shown in the photo. Make a note of this measurement, then follow Step 2 to determine the liner thickness you need.
Step 2: Choosing Your Zeta II® Liner Thickness
The Zeta II® Helmet Liner for the Military HGU-56P is available in four thicknesses: 1/4", 3/8", 1/2" and 5/8". The most common thickness we sell is 1/2". To determine the correct thickness liner for your helmet, refer table below.
NOTE: If your TPL® (Thermo Plastic Liner) has been heated and fitted, you will probably need a Zeta II® Helmet Liner one thickness thinner than listed below.
Zeta II® Helmet Liner Thickness Table
| If your TPL® Liner Has... | Then try a... |
|---|---|
| 2 Layers | 1/4" Liner |
| 3 Layers | 3/8" Liner |
| 4-5 Layers | 1/2" Liner |
| 5+ Layers | 5/8" Liner |
Once you have found the length and thickness you need, choose your Zeta II from the table below.
The sizing charts on this page are intended to suggest a starting point for the fitting process. Each individual should be fitted for comfort and stability. Results may differ from the data shown here. Oregon Aero is committed to helping you select the proper Zeta II® Helmet Liner. If you have any questions call us at 800-888-6910.
Zeta II® Size Table for Military HGU-56P(Click the part number# to order)
| 15" Styroliner (Internal Measurement front to back) | Helmet Size | ||
|---|---|---|---|
| 1/4" Thick | #9A-0015-101 | NSN 8415-01-580-5456 | XS/XXS |
| 3/8" Thick | #9A-0015-102 | NSN 8415-01-580-5460 | XS/XXS |
| 1/2" Thick | #9A-0015-103 | NSN 8415-01-580-5465 | XS/XXS |
| 5/8" Thick | #9A-0015-104 | NSN 8415-01-580-5480 | XS/XXS |
| 16" Styroliner (Internal Measurement front to back) | Helmet Size | ||
|---|---|---|---|
| 1/4" Thick | #9A-0016-101 | NSN 8415-01-580-5484 | S/M |
| 3/8" Thick | #9A-0016-102 | NSN 8415-01-580-5489 | S/M |
| 1/2" Thick | #9A-0016-103 | NSN 8415-01-580-5492 | S/M |
| 5/8" Thick | #9A-0016-104 | NSN 8415-01-580-5494 | S/M |
| 17" Styroliner (Internal Measurement front to back) | Helmet Size | ||
|---|---|---|---|
| 1/4" Thick | #9A-0017-101 | NSN 8415-01-580-5498 | L |
| 3/8" Thick | #9A-0017-102 | NSN 8415-01-580-5499 | L |
| 1/2" Thick | #9A-0017-103 | NSN 8415-01-580-5500 | L |
| 5/8" Thick | #9A-0017-104 | NSN 8415-01-580-5859 | L |
| 18" Styroliner (Internal Measurement front to back) | Helmet Size | ||
|---|---|---|---|
| 1/4" Thick | #9a-0018-101 | NSN 8415-01-590-3520 | XL |
| 3/8" Thick | #9a-0018-102 | NSN 8415-01-591-3013 | XL |
| 1/2" Thick | #9a-0018-103 | NSN 8415-01-591-3015 | XL |
| 5/8" Thick | #9a-0018-104 | NSN 8415-01-591-3020 | XL |
The Oregon Aero® Zeta II® Helmet Liner being installed in a Military HGU-56P Aviation Helmet.
Easy Installation and Care
Your Oregon Aero® Zeta II® Helmet Liner is installed in 4 easy steps using hook/loop fastner strips. Complete instructions are included with the liner. If you would like to see how easy the Zeta II® Helmet Liner is to install you can Click here to download installation instructions in PDF format.
Cleaning Instructions: Hand wash your Zeta II® 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 Zeta II® 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 II® or drying it with an artifical heat source will damage the liner. Use recommended methods of care only.