Product: GUB F1 Lightweight Cycling Half Helmet Material: high-strength PC+imported EPS foam Head circumference: One size fits all (57-61cm) Number of holes: 21 N.W.: about 338 g, G.W.: about 826 g Color: Black, White Features: PC+EPS dual protection, lightweight, multiple ventilation channels, adjustable brim, X-shaped back spoon for enhanced protection design.