Unlike a Cuban cigar, a good hard hat is not hard to find. Protective helmets or hard hats must have a hard outer shell and a shock-absorbing lining. The lining should incorporate a head band and straps that suspend the shell from 1 to 1 1/4 inches (2.54 cm to 3.18 cm) away from the user's head. This design provides shock absorption during impact and ventilation during wear. Also, hard hats should resist penetration by objects, absorb the shock of a blow, be water-resistant and slow burning and come with instructions explaining proper adjustment and replacement of the suspension and headband.