8 the screw 1 shown in fig4 differs from the screw 1 previously described especially by having a broad surface screw head 9 such screws are used especially for covering dowel fasteners and as screws for holding the backs of shelving in the case of the illustrated screw 1 due to the use to which the screw will be put the two shaft halves 4 and 5 of the threaded shaft 2 are made resiliently yielding and spread apart from one another for this purpose the threaded shaft 2 and the broad surfaced screw head 9 are made preferably from an elastic plastic or an aluminum magnesium alloy by the pressing or injection molding method if the screw 1 is made of steel the springing action of the shaft halves 4 and 5 can be produced by appropriate material selection and shaping methods or after manufacture by hardening and tempering methods important for the invention is a moldable mass 10 which is provided in the slot 3 this mass serves to lock the screw it can be provided over the entire length of the slot 3 or only over a portion of its length fig5 shows that the mass can finish flush with the outside contour of the threaded shaft 2 it is also possible however for the mass 10 to protrude slightly beyond the outer contour of the threaded shaft 2 which is shown in fig6 fig6 likewise shows two transverse bores 11 and 12 which pass through the shaft halves 4 and 5 into the slot 3 and are likewise filled with the mass 10 thus the mass 10 is reliably anchored in the slot 3 the mass 10 can also protrude slightly from.