A protective case for housing a mobile device is provided. The case comprises a shell assembly including a top shell and a bottom shell that at least partially enclose and form a perimeter around the device. The case further includes a backing assembly comprising an upper backing element and a lower backing element configured to join together along a parting line between a top end and a bottom end of the shell assembly. The case also includes a lock assembly for use in drawing together the upper and lower backing elements to hold the components of the shell assembly together.