1. Duall Shell CPSC Certified Helmet: The bike helmet features a PC dual-shell integrated design, compliant with the U.S. national standard CPSC. The dual-shell protection system provides the most reliable head protection for a more secure riding experience. 2. Lightweight PC and EPS Foam: Utilizing high-quality lightweight PC and standard 20mm EPS foam, the bicycle helmet weighs only 285g/0.63 pounds. Even during extended wear, it alleviates pressure on the head, offering excellent safety performance while enhancing your overall wearing experience. 3. Removable Sun Visor and Liner: Both the sun visor brim and liner of the helmet are designed to be removable without the need for any tools, providing convenience and efficiency. This user-friendly design not only increases the helmet's flexibility but also makes cleaning and maintenance hassle-free, offering you a more convenient user experience. 4. Adjustable Head Circumference: Our helmet features a single-handed adjustable dial fit knob and interior padding, ensuring a perfect fit for your head, making it suitable for both teenagers and adults. We recommend measuring your head circumference before purchasing; the head circumference range is 59-61cm (allow about 1cm difference).