Abstract: An expandable metal product for use in extinguishing fires and in the prevention of or protection against explosions. The product is a continuous sheet of material having discontinuous slits in spaced apart lines parallel to each other but transverse to the longitudinal dimension of the sheet. The invention is also directed to the expanded form of the product, either in sheets which may be used for preventing fires or explosion or in the form of shaped ellipsoids for use in a passive inerting system for fuel tanks, as flame arresters, as anti-explosion barriers, and as shields against mechanical impact.