CMFs typically consist of hollow spheres made of one type of metal, contained within a solid matrix composed of either the same or a different metal. They're sort of like an Aero chocolate bar, if it were made of metal instead of chocolate.One of their biggest selling features is the fact that they tend to be lighter than conventional solid metals, while offering comparable strength. Over the past few years, they have additionally been found to stop bullets, block radiation, and insulate against high temperatures.