The Bullet helmet provides an answer to the age-old dilemma of ventilation versus aerodynamicsWith its narrow shape and closed shell it is a seriously aerodynamic helmet but a quick adjustment to the Airslide system turns it into a helmet with sufficient ventilation to tackle climbs on hot daysWith four available sizes, the Bullet helmet will provide you with a snug fit and a helmet that is well fitting. This in turn creates a narrow shape with a small frontal area, creating the drop like shape of the helmetIn combination with the closed shell, this creates the aerodynamic performance to make the Bullet into a sprint helmetWhen ventilation is required, the Airslide system can be utilized to open up the front of the helmet and create an airflow throughout with exhaust vents at the rearWhen ventilation is of lesser importance, the entire Airslide system can be exchanged for a fully closed cap, creating an even more aerodynamic version of the helmetOn top of this performance the Bullet helmet also allows a quick and easy installation of the LifeBEAM technology to measure your heart rate, or the Inclination Sensor to monitor your head position on the bikeFast like a bullet, it's the perfect combination of aerodynamics and ventilation, whenever you need it!