According to Formula1, the most common type of injury is head and neck injuries. Formula One has attempted to reduce this type of damage by requiring very high standards for the drivers' helmets. The first need is that a Formula One helmet be exceedingly light. This advancement creates the problem of developing a product that is also as tough as it has to be. The helmets must pass a series of fragmentation and deformation tests to guarantee that they fulfill the stringent criteria. Because of its strength, carbon fibre is the principal material used to build Formula One helmets. The exterior shell is made up of two layers, the majority of which are made of carbon fibre.