GameBreaker Stealth – Hard Shell Helmet Liner


The GameBreaker Stealth Helmet Liner is a helmet insert fully powered by an innovative smart molecule technology. D3O® materials flow freely when at rest, but on impact, lock tightly together to disperse and absorb the energy of the blow, before instantly returning to their soft, flexible state. This reaction is instantaneous and 100% passive. The greater the force of impact, the greater the protection. The helmet padding insert liner has the ability to reduce the SI (severity index) while fitting comfortably inside all helmets, caps, or beanies.

  • PROTECTED BY D3O (Learn More about D3O)

Currency conversions are estimated and should be used for informational purposes only.

Add the Stealth helmet liner to helmets, beanies & More

Add the power of D3O impact protection to any hard shell helmet, hat or beanie with military grade D3O impact protection. The stealth helmet liner insert provides protection for helmets of all sports from football and hockey to motocross or even snowmobiling.

Installing A STEALTH helmet liners is SIMPLE

The GameBreaker Stealth Helmet Liner is a universal, one size fits all product. Easily trim off any unwanted excess D3O® with any pair of scissors. Fits helmets, caps, and beanies.

With a GameBreaker Stealth helmet liner there is no need to modify your existing helmet. The only tools required are a marker and a pair of household scissors or utility knife. Never fear voiding warranties or damaging expensive helmets again.

● Start by placing the Stealth Helmet Liner inside your existing helmet with the orange side facing out.
● You may choose to put the helmet on at this stage to ensure that the liner is fully seated in a position that is comfortable for you.
● Using a permanent marker, trace a line along the edge of the helmet marking any overhanging parts of the liner.
● Remove the Stealth Helmet Liner from your helmet.
● Use scissors or a utility knife to follow the lines you drew and trim off any excess D3O® from your Stealth Helmet Liner.
● Reinsert your trimmed Stealth Helmet Liner with the printed comfort liner facing out.

football helmet liner diagram


The performance of two national brand hard shell football helmets was improved by up to 17% in high and low-velocity impacts when compared to the effectiveness of the helmet without a Stealth Helmet Liner.


The GameBreaker Stealth Helmet Liner reduced the severity index score across all four testing zones:
Rear Boss, Front Boss, Front, and Side*. 

*see graphic below for comparisons

FAQs About Bicycle Helmet Liners

If you have questions about our bicycle helmet liners, we want to help. That’s why we have answered a few of the most common questions we hear from customers.

Can GameBreaker Stealth Helmet Liners Be Removed and Reinserted Easily?

Absolutely. Stealth helmet liners are designed for convenience. You can easily remove and reinsert them for cleaning or replacement, ensuring that your helmet remains fresh and ready for your next ride.

Do GameBreaker Stealth Helmet Liners Come in Different Sizes?

No, the GameBreaker Stealth Helmet liner is a one size fits all product. Designed to fit helmets that range from full head coverage football helmets, to skull caps, they even fit the most streamlined bicycle racing helmets. Stealth helmet liners are easy to trim to fit any helmet!

Are Your Stealth Helmet Liners Suitable for Different Types Helmets?

Yes, our helmet liners are versatile and suitable for various types of activity, whether it’s skateboarding, mountain biking, rock climbing, skiing, or playing full contact football. The enhanced protection and comfort benefits apply to all cycling activities.

Can GameBreaker Helmet Liners Be Used by Both Adults and Children?

Absolutely. GameBreaker helmet liners are designed to provide improved safety and comfort for athletes of all ages. Whether you’re an adult or a child, these liners can enhance your sporting experience while prioritizing head safety.

order the Stealth helmet Liner insert today

Purchase the GameBreaker stealth helmet liner insert today for increased head protection. It’s simple to install and affordable for one athlete or an entire team. Submit your order or contact us if you have any questions.

Additional information

Weight 0.25 lbs
Dimensions 15.0 × 13.0 × 0.5 in