Energy Dispersement Ridge - Adds strength and stability; conforms to head contour. Rear Helmet Shell Offset - Conforms to shape of rear skull. Newly Designed Polycarbonate Anatomically Correct Shape - Reduced weight for comfortable fit. Skeletal Sub Structure (SSS System) - Expanded Polypropylene - Light weight stiff skeleton supports shell and assists in attenuating impacts. Stainless Steel Hardware Snap Posts for Use with 4-Point High and/or Low Hook-up Chin Strap.