Thank you for viewing. Please refrain from purchasing if you are concerned about home storage. Size M (52-58cm) - Outer shell: High-density ABS / Inner shell: EPS for shock absorption - 3D all-around protection, 2 sets of replacement liners 8mm and 4mm (washable) - Improved Asian fit: Reduced pain, improved safety, prevents "mushroom head" appearance - 11 ventilation holes + all-around adjuster for reduced stuffiness & secure fit - Suitable for children to adults / Ideal for commuting, cycling, skateboarding, etc.