- A rigid shell that resists and deflects blows to   the head; 
- A suspension system inside the hat that acts as   a shock absorber;
- Some hats serve as an insulator against   electrical shocks;
- Shields your scalp, face, neck, and shoulders   against splashes, spills, and drips; and 
- Some hard hats can be modified so you can add   face shields, goggles, hoods, or hearing   protection to them.