Type I hard hats are used to reduce the force of impacts from falling overhead.
Class E hard hats are used for electrical applications and protect against contact with high voltage conductors. They have the highest rating and are tested at 20,000 volts AC for three minutes. Class E hard hats also meet Class G and Class C regulations. Class E was formerly designated Class B.
Ratchet adjustments systems are designed with a knob for turning and locking into place.