Alpinestars - S-M3 Radium Helmet

Alpinestars - S-M3 Radium Helmet

The S-M3 Radium Helmet is built for riders who want a modern off-road helmet with serious protection and a clean, aggressive look.

Designed for riders who demand premium protection and performance, the Alpinestars S-M3 Jettson Helmet delivers advanced safety technology in a lightweight, ventilated package. Its thermo-injected polymer shell features variable thicknesses to maximize impact protection while minimizing weight-just 1430g (ECE) and 1460g (DOT) in a size medium.

Why We Like It

We like this helmet because it feels secure without being overly heavy, and the venting actually works when you’re charging hard.

Why It’ll Work for You

If you’re after a helmet that can handle moto days, off-road loops, and everything in between, this one gives you dependable protection and comfort.

Variants / Options

Available in multiple shell sizes and graphics so you can get a confident fit and a look that matches your style.

Key Features

• Advanced Shell Construction: This 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 lightweight. The SM3 medium weighs 1430g (ECE) and 1460g (DOT).
• Ventilation: Maximized ventilation and high levels of heat transfer exchange thanks to 10 inlets and seven exhaust ports.
• Rotational Acceleration Force Protection: 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.
• Visor Release: 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.
• The inner and outer surfaces are engineered to minimize the effects of oblique impacts.
• 5 EPS inner parts with 4 densities to effectively manage volume and impact perfromance.
• Hydration tube channels are integrated into the helmet’s cheek pads for convenience and performance.
• Comfort liner is constructed using recycled materials for a lower carbon footprint.
• 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.
• Alpinestars has introduced a new in-house standard for the SM3 helmet 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.
• The inner and outer surfaces are engineered to minimize the effects of oblique impacts.
• Equipped with an EUPDATEncy 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.
• The SM3 helmet conforms to both DOT certification and ECE 2206 homologation for use worldwide.