2026 Alpinestars A-4 Plasma Chest Protector SIZES: M = M/L XL = XL/2XL Description Anatomically profiled for all forms of off-road riding, the A-4 PLASMA Chest Protector features a semi-rigid thermoplastic polyhedron design chest protector and a Nucleon PLASMA back protector that are engineered to be lightweight, breathable, comfortable, adaptive, and protective. Key features Exceptional Comfort and Flexibility: The Nucleon PLASMA Back Protector is crafted from a USDA Certified Biobased viscoelastic material. Designed for multi-directional pliability, the protector molds to the body for a close fit, effectively dissipating impact energy to deliver reliable protection. Lightweight and highly ventilated, this protector offers strong impact force dispersion and absorption while ensuring maximum coverage area in all riding positions. Lightweight and Ultra-Ventilated Chest Armor: The chest outer shell’s design is based on geodesic polyhedrons, and like a geodesic dome, less material is needed to achieve the desired structural strength and imposed load performance when compared to flat or unfaceted surfaces. This results in a protector where the whole is greater than the sum of all its parts, making the new A-4 PLASMA Chest Protector supremely lightweight and ventilated. Premium Comfort: The over-injected flexible side wings of the chest protector perfectly follow the body’s contours for superior comfort and freedom of movement. Optional Race kit: Engineered to be compatible with the Nucleon PLASMA Extended Roost Coverage kit which includes Upper and Lower Chest Extensions and an additional Y-Strap System, allowing riders to use the A-4 Chest Protector without the back protector. Rib and Shoulder Coverage: The A-4 PLASMA Chest Protector features highly perforated, adjustable, and detachable rib and shoulder padding for additional coverage against roost and impact. BNS compatible via the elasticated BNS pull tabs situated on the removable soft tactile thermoformed shoulder pads. Construction Constructed from Certified Biobased, eco-friendly and sustainable impact absorbing material. Equipped with adjustable shoulder and side straps for an optimized performance fit. Removable soft tactile thermoformed shoulder padding for enhanced rider comfort. The lining on the back protector offers a soft tactile feeling against the skin while maintaining the integral structure of the protectors and reducing the risk of any material tearing. The lining is ribbed for superior airflow while also reducing the amount of material that is in contact with the skin. The perforated 3D mesh chassis also offers additional protection against tire roost. Bionic Neck Support compatibility via the BNS shoulder pull tabs. Protection According to European statutory law, the CE mark is a conformity requirement for the marketing of this product. The following standards apply: Back protector: EN 1621-2:2014 LEVEL 1 Chest protector: EN 1621-3:2018 LEVEL 1