Abstract: A rockbolt for anchoring in a borehole and then tensioning it has a nut at its distal end whose screw threaded engagement with the rockbolt is utilised to force the nut against the surface at which the borehole is provided and cause tensioning of the rockbolt. Initially, the nut cannot be run down the rockbolt owing to provision of a disc seated in a recess at the distal end of the nut and which is only forced out from the recess when the nut is subject to a minimum predetermined torque. Holding of the disc in the recess is achieved by deformations of the nut resulting in the perimeter of the disc being frictionally restrained.