A KEY PLUG, A CYLINDER LOCK, A CYLINDER LOCK AND KEY COMBINATION AND A METHOD TO MANUFACTURE A KEY PLUG

A key plug rotatable within a cylindrical bore of a cylinder lock. An upper relatively narrow part of a keyway has a small lateral width no more than 33% of the maximum width of a lower relatively wide part of the keyway and extends obliquely upwards along a first direction pointing away from a second lower side wall of a lower part and being inclined at a relatively small angle a, in the interval 3° to 12°, relative to the vertical mid-plane. The sideways or lateral location of the upper relatively narrow part of the keyway is such that an imaginary downward extension thereof, substantially in a second direction opposite to the first direction down to an outer cylindrical contour of the key plug, will fall onto the outer cylindrical contour at a same second side of the vertical mid-plane and inside the second lower side wall of the keyway.