Cratoni c bolt helmetbest ventilation for an unbeatable priceour c bolt unites low weight with best ventilation and appeals to ambitious road cyclists on the search for an optimum regarding price and performance besides a sophisticated ventilation system with enormous air vents further highlights are a smoothly running one hand adjustable system plus high quality antibacterial pads features 21 vents reflectors strap divider inmolded strap anchors incl bag size sm 53 56cm ml 56 59cm lx