A sandwich panel is a kind of composite material, which is usually made of two components: A small outside layer (which is the same on both sides), and an inside layer, which is used to get certain properties, for example insulation or fire resistance. Aluminium is often used for the outside part - the respective panels are also known as Aluminium Composite Panels. Sandwich panels are used in situations where high structural rigidity and low weight are required. They are also used for cladding, eg. to add insulation, fire resistance, or simply to make a surface look more beautiful.