Technology : Composite Fusion Plus - Incorporates layers of multi-density cone shaped EPS foam, reduces impact g-forces up to 25%Features: Internal structural cage Anti-microbial pads Bug liner Locking buckle & sliders Locking slidersMaterial: PC shell & bottom wrap EPS foamRetention: Micro-fit closure systemVents: 21Sizes:S/M 54-58cmL/XL 58-62cmWeight: 250 grams