For BMX and mountain biking, the Troy Lee Designs D2 Bike Helmet sets the bar high for durable, lightweight, full-face helmets. With an aerospace composite shell and high-flow ventilation system incorporated into both the shell and liner it'll feel practically weightless. The large eye port and adjustable Orbit visor allow for optimal visibility on the course or in the mountains, making the Troy Lee Designs D2 Bike Helmet a stylish, stealthy, and sturdy skull-protector.