The document discusses different classes of biosafety cabinets. A Class II biosafety cabinet has HEPA filters that protect the environment by filtering air before exhaust. It is portable and easy to operate. A Class IIA biosafety cabinet provides downflow HEPA filtered air to protect products and exhaust HEPA filtered air to safeguard the working environment. A Class IIB biosafety cabinet offers the highest level of protection for users and the environment from hazardous pathogens through customization.