
ALPINESTARS(MX) Youth S-M3 Radium Helmet — Black, Blue, Yellow, L
In stock items will be shipped within 1-3 days.
You can return the products within 14 days for a full refund, check our returns policy.
We accept many payment methods

In stock items will be shipped within 1-3 days.
You can return the products within 14 days for a full refund, check our returns policy.
Anatomically engineered and profiled specifically for youth and younger riders, the all-new SM3 Youth Helmet is optimized for MX, Enduro and Off-road use.
This lightweight helmet features a thermo-injected shell incorporating a special polymer blend enhanced by varying degrees of thickness that is engineered to deliver the optimal combination of impact protection and light weight.
Lightweight outer shell is constructed from a technologically advanced impact resistant thermoplastic in three sizes (Youth Small, Youth Medium and Youth Large). The SM3 Youth weighs 1060g.
The fit can be tailored to the rider’s head thanks to the helmet’s crown and cheek pads, which are available as genuine spare parts in different thicknesses.
Youth Medium and Youth Large sizes share the same EPS size, which allows riders with an YM size to initially buy an YM helmet and then configure it to a Youth Large size as they grow via the crown and cheek pad spare parts.
The Youth Small has a smaller EPS size and can be customized only via the cheek pads. Alpinestars extensive research has shown that the kids that wear a YS size are very small, typically 3 to 4 years old, and therefore they require a dedicated helmet fit.
Multiple density inner liner ensures the helmet is equipped with the correct density in the correct area for enhanced impact absorption, while also helping reduce overall weight.
The inner and outer surfaces are engineered to minimize the effects of oblique impacts.
Alpinestars patented low friction coating is applied to the inner part of the main EPS liner to reduce the rotational acceleration forces that can result from certain oblique impacts. This layer essentially acts as a slip plane to mimic the brain’s own low friction cerebrospinal fluid, which is the body’s natural defense against oblique impacts.
Patented visor release system ensures the visor is released with the correct pre-determined amount of force, effectively reducing the forces on the rider’s neck during an impact.
Comfort liner is constructed using recycled materials for a lower carbon footprint.
Hydration tube channels are integrated into the helmet’s cheek pads for convenience and performance.
Safety
Alpinestars has introduced a new in-house standard for the SM3 Youth to test the helmet’s chin to conditions heavier than the homologation standard, and in order to pass the Alpinestars’ new standards, the shell thickness and the structure of the helmet design itself have both been optimized on the chin area for superior impact performance.
Equipped with an Emergency Release System and removable cheek pads to permit the safe and easy removal of the cheek pads while the helmet is still on, while the 3D contoured foam ensures rider comfort.
Soft textile chin strap is 25mm for optimal safety and rider comfort.
Stainless steel D-rings ensure a tight and secure fit.
Ventilation
Maximized ventilation and high levels of heat transfer exchange thanks to 10 inlets and seven exhaust ports.
The visor has been designed to direct air into the ports for enhanced airflow.
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We do not ship to the Canary Islands, Ceuta, or Melilla.
Shipping costs are calculated automatically at checkout based on destination and weight.
Free shipping may be offered for qualifying orders, as specified on our website.
Orders are processed within 1–2 business days after payment confirmation. Orders placed on weekends or public holidays are processed the next business day.
If your order is delayed or arrives damaged, you must notify us within 14 calendar days. We will investigate the issue and offer a resolution in accordance with applicable consumer protection laws.
In accordance with Royal Legislative Decree 1/2007 (Ley de Defensa de los Consumidores y Usuarios), you have the right to withdraw from your purchase within 14 calendar days from the date of receipt, without giving any reason.
To exercise this right, contact us via email or through our website, providing your order number and contact details.
If you want to return an item, please contact us first to give you detailed instructions.