Description Like every GPA helmet, the 4S was developed with maximum protection as the focus. The 4S is a technological revolution with its 4 layers which enable optimum shock absorption as well as better resistance to lateral compression. Unparalleled damping The outer shell, made of absorbent polymer, absorbs the first part of the shock by deforming. The 2nd layer takes up the energy of the impact and absorbs it. The 3rd layer, made of fibreglass, ensures the rigidity of the entire helmet to avoid lateral compression. The 4th layer is the polystyrene shell which completes the deceleration of the shock by crumpling under the impact, thus protecting the cranial vault from brain injuries. An optimal ventilation system Thanks to its numerous front and side vents and its rear outlets, this helmet offers maximum ventilation. Unparalleled comfort This new one-piece, and removable, liner is washable and can be replaced if needed. The soft and fluffy inner has been been given an antibacterial treatment. Better neck protection and increased hold The classic chinstrap is replaced by a hybrid system, a new exclusive from GPA. A cross between the twin lock system and the traditional chinstrap, its rear part is made of thermoplastic resin and incorporated fibreglass fabric. Its nylon straps, covered with synthetic leather, fasten by means of a two-part buckle. Thanks to its rigid part at the back which extends the shell, this hybrid chinstrap guarantees more extensive protection and better support for the helmet on the head. Its more affordable price and design will win over the more conventional riders as well. Technical description: The range of GPA helmets complies the draft standard EN1384-2017. The GPA range of helmets complies with the current American standard ASTMF1163-15 and is also SEI (American quality label) approved. Please order 1 size up as the helmets run small. Product ID: 345583 Product reviews (0) GPA 4S Speed Air Hybrid Riding Helmet