This standard provides performance and testing requirements for industrial helmets, commonly known as hard hats. It establishes the types and classes of protective helmets, depending on the type of hazard encountered. It includes specifications for helmets designed to offer protection from lateral impact, or top-only impact, giving employers and users the flexibility to specify the helmet that best meets the needs of their specific workplace. ANSI/ISEA Z89.1-2009 serves as a revision to ANSI Z89.1-2003. Key updates contained in this version include optional testing and marking features for head protection devices that reflect end-user preferences. In addition, the revised standard includes criteria for products that can be worn in the reverse position.