Abstract: A mine roof support system which includes a steel anchor rod and a threaded fastener. The rod has a threaded end portion, and which is adapted for positioning in a bore hole so that the threaded end portion projects outwardly from a rock face. The threaded fastener includes a body having a pair of opposing end portions and a bore which extends along its central axis. Internal threads complimentary to those on the rod are formed along part of the axial length of the bore, whereby the relative rotation of the fastener and rod moves the rod axially through the bore. A cap member is detachably coupled to one end portion of the fastener covering part of the bore. When coupled, the cap member acts as a positive stop which limits relative movement of the rod axially through the fastener bore, and which when detached allows the fastener to run freely along the threaded portion of the rod.