Abstract: A roller bearing assembly configured to guide linear movement of a shaft with a polygonal cross section. The roller bearing assembly includes a housing unit, which may contain a centrally-placed hole for mounting the assembly, and a plurality of cavities on the surface of both ends of the housing unit. The bearing assembly further includes a plurality of axially-displaceable roller bearings placed in one or more sets of pairs in the cavities of the housing. The roller bearings contact the shaft to guide movement axially and to resist torque, and thereby prevent the rotation of the shaft relative to the housing unit.