The invention relates to a fastener for joining together two components, for example two at least locally flat components.  The fastening includes a closure pin lockingly securable to a first component and a receptacle disposed on the far side of a second component.  The closure pin has a head section adapted for support an outer side of the first component and a shank section extending through a hole in the first component or a guide sleeve disposed in the hole in the first component and through a hole in the second component aligned with the hole in the first component or the guide sleeve.  The shank section has a thread mating with an internal thread in a fastening section of the receptacle.  A peripheral surface of the closure pin has a radial taper with a stop face radially extended on the opposite side from the head section and formed by a rim stop.  The stop face engages with a safety element to prevent complete extraction of the closure pin from the hole in the first component or the guide sleeve.  The safety element is inserted, preferably under radially inward pre-stress, in the hole in the first component or the guide sleeve and disposed in a groove open to the hole in the first component or the guide sleeve. 
A fastener of this type is known.  In such known fastener, the closure pin is held in the first component by a radially inwardly pre-stressed safety ring of rectangular or square cross-section, which is disposed in an annular groove formed in a guide sleeve fitting in the first component and engages with a radial taper on the shank section of the closure pin.  On extracting movement of the closure pin from the hole in the first component or the guide sleeve, the safety ring initially slides along a cylindrical zone of the shank section, until it encounters the zone of the radial taper, onto which it contracts by reason of its pre-stress.  Complete withdrawal of the closure pin from the hole in the first component is prevented by the widened stop face, which is engaged by the safety ring lying tightly round the tapered zone of the closure pin.  Thus, the closure pin can be withdrawn until the safety ring encounters the above-mentioned stop face, but is then permanently held within the hole in the first component.  The known fastener is defective in that the closure pin can never be removed from the first component without being more or less destroyed.  To effect removal, one must take off, for example saw off, either the head section or the rim stop on the other end of the closure pin, which on the one hand costs time and money and on the other hand renders the closure pin unfit for further use.