ANSI Z89.1 splits hard hats into two impact types and three electrical classes. Most guys never read the label inside the shell. The label is the difference between protection and decoration.
Type I is rated for impact from above only. A wrench falling out of an upper-floor pocket. A loose bolt. A tool slipping off a steel beam. The shell distributes the impact across the suspension and down to your shoulders. Type I is the most common rating in North America — it's what the typical white or yellow construction hat is.
Type II is rated for impact from above and from the side. The internal foam liner extends around the inside of the shell, not just under the crown. Type II is more common in Europe and is becoming more common on US jobsites, especially for utility, industrial, and any work where lateral impact (a swung beam, a fall against scaffolding) is a real risk. If your safety officer specifies Type II, a Type I is not a substitute.
Class G is general — protects against contact with low-voltage sources up to 2,200 volts. Class E is electrical — up to 20,000 volts. Class C is conductive — no electrical protection at all, but lighter and ventilated, used in non-electrical environments where airflow matters. Wear a Class C around live electrical and you're a hazard to yourself.
Cap style versus full-brim is the shape question. Cap style has a short brim only at the front, like a baseball cap. Full-brim has a brim all the way around, like a cowboy hat or a sailor's hat. The question is sun and rain.
Full-brim sheds water away from your face and neck better than a cap, and the brim shades your shoulders and the back of your neck — useful for outdoor work in summer and rain. Cap style is more common indoors and in tight spaces because the back brim doesn't catch on overhead obstructions.
If you're outside year-round, full-brim. If you're crawling into duct chases and equipment rooms, cap. If you're both, pick whichever is more frequent — neither is wrong.
Hard hats expire. The shell has a manufacture date stamped inside. Most manufacturers say the shell is good for five years from manufacture, two to three years from first use. UV breaks down the plastic. After that the shell can crack rather than deflect on impact. Replace it.
We carry both types and both shapes. Most jobs accept either, but if your spec says Type II, bring the spec.