2nd Skull® Pro Cap
- Developed with NFL
- Impact Absorbing Technology
- Ultra-Lightweight
Info
The 2nd Skull® Pro Cap was engineered with a $100,000 NFL grant as winner of the NFL HeadHealthTECH Challenge II.
Building on our original 2nd Skull® Cap, it delivers improved airflow and premium breathable fabrics for greater comfort. In NFL testing, the Pro Cap performed in the same heat-index category as skull caps and wraps that offer no impact protection at all.
Designed to fit comfortably under any helmet, the Pro Cap has been worn by professional players — including in Super Bowl LIV.
At its core is thin, 2mm XRD® Extreme Impact Protection. Flexible at rest, the material instantly stiffens under sudden pressure to help mitigate impact, while its low profile keeps helmet fitting seamless. The moisture-wicking fabric conforms to your head and keeps you cool.
Focus on your performance with the 2nd Skull® Pro Cap.
Features
- Developed with NFL as Winners of NFL HeadHealth Tech II Challenge
- Impact Absorption Technology
- Ultra-Lightweight: under 3 oz
- 2mm low-profile design fits comfortably under most helmets
- Improved airflow and premium breathable fabric
- Moisture-wicking fabric keeps you dry
- Antimicrobial treatment to help prevent odor
- Designed after the accessories pros already wear
- Permitted for High School use by NFHS
- Multi-sport: football, hockey, baseball, lacrosse, and more
- Fabric: 80% Nylon, 20% Spandex
- Hand wash only
- Made in the U.S.A.
Size Chart
| 2nd Skull Pro Cap | Inches | Centimeters |
|---|---|---|
| Youth | 19” - 21” | 48.3 - 53.3 cm |
| Teen/Adult | 21” - 24.5” | 53.3 - 62.2 cm |
| X-Large | 24.5” - 26” | 62.2 - 66.0 cm |
Conversion: 1 inch = 2.54 cm, rounded to 0.1 cm.
Find Your Perfect Fit
Measure your head circumference 1 inch above your eyebrows using a soft tape measure. If you're between sizes, choose the larger size.
| 2nd Skull Pro Cap | Inches | Centimeters |
|---|---|---|
| Youth | 19” - 21” | 48.3 - 53.3 cm |
| Teen/Adult | 21” - 24.5” | 53.3 - 62.2 cm |
| X-Large | 24.5” - 26” | 62.2 - 66.0 cm |
Conversion: 1 inch = 2.54 cm, rounded to 0.1 cm.
WINNER NFL HEADHEALTH TECH II CHALLENGE
2nd Skull vs. Over the Helmet Protection
The 2nd Skull® Pro Cap was worn in Super Bowl LIV. 2nd Skull® provides ultimate versatility under any sports helmet and is not limited to practice.
| Feature |  |
OVER THE HELMET PROTECTION |
|---|---|---|
| Multi-Sport | ||
| In Game | ||
| Lightweight | ||
| Helmet | ||
| Made in USA | ||
| Price Range | $89.95 | $89.99* (Pro Version) |
Trusted by pros and athletes at all levels
See how athletes use the 2nd Skull® Pro Cap to stay protected without losing their competitive edge. Real protection, real results.
2nd Skull® Pro Cap
NFL-engineered, lightweight protection designed to fit comfortably under most helmets.
NFL-Engineered Protection
Developed with NFL as Winners of NFL HeadHealthTECH II Challenge
Impact Absorbing Technology
Features a 2mm layer of XRD® Extreme Impact Protection; helps absorb impact forces when impacted.
Ultra-Lightweight
Under 3 ounces, it let's you play at your fastest version.
Helmet-Ready Performance
Thin profile supports a seamless helmet fit.
NFL-Tested Protection
Pro-Level Defense, Seamless Helmet Fit
The 2nd Skull® Pro Cap delivers lightweight, impact absorbing protection. Its low-profile construction fits comfortably under helmets without adding unnecessary bulk.
Used in Super Bowl LIV
Developed with NFL as Winners of NFL HeadHealth TECH II Challenge and trusted at the highest levels of play
Serious Protection Without Bulk
A 2mm layer of XRD® Extreme Impact Protection helps absorb sudden impacts while maintaining a lightweight, flexible feel.
Multi-Sport
Stay protected throughout the year. For football, baseball, hockey, lacrosse, softball and more.
FAQ
Got quick questions? Here is everything you need to know about 2nd Skull protection, fit, and care.
How does 2nd Skull® Technology work?
2nd Skull® uses an independent floating protective layer nested between two fabric layers. Because this protective layer floats independently rather than being fixed in place, it allows slippage on impact—which is what lets it guard against both rotational impacts (angled or twisting forces) and linear impacts (direct, straight-on hits).
The protective layer itself is made of XRD® Extreme Impact Protection material. The advanced material is soft and flexible during normal use, but upon impact, it instantly hardens to absorb and dissipate the energy from the impact. It then returns to a soft state.
Will it fit comfortably under my helmet?
Yes. Both the 2nd Skull® Cap and 2nd Skull® Pro Cap are designed to be worn under sports helmets without having to upsize. They fit seamlessly under any standard helmet (football, hockey, baseball, lacrosse and more) without changing your helmet size.
Can I use it for multiple sports?
Absolutely. It is a multi-sport protective gear. And works under sports helmets such as football, hockey, baseball, softball, lacrosse, and more.
How do I wash and maintain it?
We recommend hand washing it with cold water and a mild detergent, then letting it air dry. Do not put it in the dryer, as high heat can damage the protective XRD® material.