Examples disclosed herein provide a hinge mechanism to pivotally connect housings of a computing device along an axis. As an example, the hinge mechanism includes a guide rail fixed to the first housing, a base block fixed to the second housing, and a rotary element to constrain the guide rail to the base block, wherein the guide rail and the base block are concentric along the axis, and the guide rail is to rotate around the base block. As an example, the hinge mechanism includes a rotation assembly comprising a slot on one end to receive a pin of the guide rail in order to link the guide rail to the rotation assembly. As an example, the rotation assembly is to provide a level of resistance to a torque provided when opening or closing the first housing with respect to the second housing.