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.