structural:expansion
Back cover materials

Back covers of smartphones are typically made of polycarbonate, aluminium, or glass. Polycarbonate back covers may be glossy or matte, and possibly textured, like dotted on the Galaxy S5 or leathered on the Galaxy Note 3 and Note 4.

While polycarbonate back covers may be perceived as less "premium" among fashion - and trend -oriented users, its utilitarian strengths and technical benefits include durability and shock absorption, greater elasticity against permanent bending like metal, inability to shatter like glass, which facilitates designing it removable; better manufacturing cost efficiency, and no blockage of radio signals or wireless power like metal.