MAXAM’s Model FHD4R fire rated floor doors are tested for a four-hour fire rating. These models control the transmission of heat, hot gases, and flames when installing in a rated floor-ceiling assembly. Tested and listed to the first ever 2001 edition of NFPA 288 test standard. The FHD4R allows for access to equipment and crawl spaces and has been sturdily built to ensure quality and dependability. Tailored to offer simple installation for various design and installation requirements. For standard sized products, heavy duty stainless steel gas cylinders are standard for a 90° opening. All sizes are not available with the optional self-closing mechanism.