The Ribcap is a soft, flexible cap that hardens on impact to protect the head from damage. The secret lies in the use of an elastomeric compound called d3o. It was discovered by researchers at University of Hertfordshire. It’s a shear thickening material, which is flexible when moved slowly, but when it is compressed by an impact, its molecules lock together.
The material stiffens, spreading the impact over a greater area. The Swiss company Ribcap is bringing out a new line of headgear for snowsports based on this material. You can read more about it on their website.