Portable Airbag

This is an actual thing for bicyclists.

The airbag is shaped like a hood that surrounds your head. It's made in an ultra-strong nylon fabric that won't rip when scraped against asphalt. The way the hood is designed and folded into the collar ensures that it will inflate quickly and safely. It takes about 0.1 seconds to inflate and the airbag will be fully inflated before head impact. Hövding protects nearly all of the head while leaving the field of vision open. The airbag provides soft and effective shock absorption and maintains constant pressure for several seconds, making it able to withstand several impacts to the head in the same accident.

Before it inflates, it looks rather like a neck brace.