Examples disclosed herein provide a hinge mechanism to couple housings of a computing device. As an example, the hinge mechanism includes a first guide rail fixed to a first housing of the computing device, a second guide rail fixed to a second housing of the computing device, and an intermediate guide rail to connect the first and second guide rails to each other. As an example, the hinge mechanism includes clamping brackets to hold the first, second, and immediate guide rails together and apply rotational friction to the hinge mechanism so that the first and second housings can be positioned at various angles with respect to each other.