A locking apparatus for introduction into a recess of a device to be locked, the locking apparatus having: an actuating pin as well as a bolt part which is rotatably fixedly connectable to the actuating pin and which can be locked and/or unlocked by rotating the actuating pin, wherein the bolt part can be fastened in a plurality of positions at the actuating pin, the actuating pin and the bolt part have releasable latching means having a plurality of latching positions for latching the bolt part in a plurality of axial positions at the actuating pin, and the latching means have latch contours which engage into one another in a shape-matched manner, which can be pushed beyond one another in the longitudinal direction of the actuating pin under elastic deformation and which can latch into one another by elastic spring back transversely to the longitudinal direction of the actuating pin, wherein the actuating pin has a rotary guide part associated with it which can be plugged into the named recess with an exact fit and has latching means for latching to a marginal contour surrounding the recess, characterized in that the latching means of the rotary guide part comprise a plurality of latch projections which project radially at the peripheral side from the carcass of the rotary guide part and which are arranged staggered behind one another in the longitudinal direction of the rotary guide part such that a respective other latch projection can be latched with an exact fit with marginal contours of the recess of different thicknesses, and are radially elastically deformable on the axial plugging of the rotary guide part into the recess and snap back radially after passing through the recess. an actuating pin as well as a bolt part which is rotatably fixedly connectable to the actuating pin and which can be locked and/or unlocked by rotating the actuating pin, wherein the bolt part can be fastened in a plurality of positions at the actuating pin, the actuating pin and the bolt part have releasable latching means having a plurality of latching positions for latching the bolt part in a plurality of axial positions at the actuating pin, and the latching means have latch contours which engage into one another in a shape-matched manner, which can be pushed beyond one another in the longitudinal direction of the actuating pin under elastic deformation and which can latch into one another by elastic spring back transversely to the longitudinal direction of the actuating pin, wherein the actuating pin has a rotary guide part associated with it which can be plugged into the named recess with an exact fit and has latching means for latching to a marginal contour surrounding the recess, characterized in that the latching means of the rotary guide part comprise a plurality of latch projections which project radially at the peripheral side from the carcass of the rotary guide part and which are arranged staggered behind one another in the longitudinal direction of the rotary guide part such that a respective other latch projection can be latched with an exact fit with marginal contours of the recess of different thicknesses, and are radially elastically deformable on the axial plugging of the rotary guide part into the recess and snap back radially after passing through the recess.