This Helmet Knows When It's Too Damaged To Protect Your Head

Helmets made with a liner material called expanded polystyrene will protect your head during a ski accident, but need to replaced after the first major impact. Helmet liners made from expanded polypropylene, though, can endure multiple impacts before needing a replacement. Using a series of sensors inside its liner,… » 3/11/14 5:40pm 3/11/14 5:40pm