The F2 Grease Duct Sandwich Access Door is for grease duct applications and meets NFPA 96 standards.? Its ceramic fiber gasket allows its use with temperatures up to 2300?F.? Please specify when ordering the F2 door for use with a duct wrap system - longer bolts will be applied. Used to provide easy access into grease duct. Access door application approval resides with the authority having jurisdiction.