A key for use in a cylinder lock with a rotatable key plug having an elongated key blade with a relatively wide lower portion and a relatively narrow upper portion. A step-like transition region between the wider lower portion and the narrow upper portion. The key blade includes a longitudinal profile groove located adjacent to the step-like transition region that extends along at least a portion of the length of the blade. An inner wall of groove is substantially parallel to a side surface of the lower portion of the key blade. The longitudinal profile groove includes an undercut portion adjacent to and inside a ridge portion of the key blade. The outside of ridge portion forms apart of the side surface of the blade in the relatively wide lower portion up to the step-like transition region and the inside of ridge portion facing inner wall of the groove.

Cylindrical locks and more specifically a set of profile members in combination with a rotatable cylindrical key plug have a longitudinal keyway with a profile corresponding to an associated key. Each profile member is accommodated in an associated cavity in the key plug at a lateral side of the keyway so as to form a lateral part thereof. The profile members have a non-circular cross-section and are non-rotatably mounted in the associated cavities at a location adjacent to the keyway. A portion of each profile member has a profiled surface portion facing inwards toward the opposite lateral side of the keyway, the profiled surface portion having, in a plane being transversal to a longitudinal axis of the key plug, a specific profile section defining a local, lateral part of the keyway. An associated key, and a method to manufacture a cylindrical key plug with such profile members are also disclosed.

A key for use in a cylinder lock with a rotatable key plug having a profiled keyway. The key comprises an elongated, substantially flay key blade (120; 120) having a longitudinal profile groove (122; 122) extending along at least a portion of the length of the key blade. The groove has an undercut portion (129) adjacent to a ridge portion (128, 128), the outside of which forms part of a side surface (123; 123) of the key blade. The undercut portion (129; 129) of the groove is expanded, at its innermost part adjacent to and inside said ridge portion, into a longitudinally extending pocket (135; 135).

A flat key for a locking cylinder has substantially flat and approximately parallel flat key sides, a key rear section, and a key front section opposite thereto. The key front section has a toothing for positioning tumbler pins divided into core pins and housing pins and which are spring-loaded against the key front section in the direction of the key rear section and into corresponding bores. Grooves in the form of profiled variation elements and profiled guiding elements are provided in the flat sides of the flat key, wherein at least two grooves of one flat side of the flat key, which are preferably part of the profiled guide, overlap and are undercut in opposite directions. A depression is provided in the outer flank of at least one of the two grooves, preferably both grooves, at least one region of the depression not being visible from the side.

A flat key for a locking cylinder has substantially flat and approximately parallel flat key sides, a key rear section, and a key front section opposite thereto. The key front section has a toothing for positioning tumbler pins divided into core pins and housing pins and which are spring-loaded against the key front section in the direction of the key rear section and into corresponding bores. Grooves in the form of profiled variation elements and profiled guiding elements are provided in the flat sides of the flat key, wherein at least two grooves of one flat side of the flat key, which are preferably part of the profiled guide, overlap and are undercut in opposite directions. A depression is provided in the outer flank of at least one of the two grooves, preferably both grooves, at least one region of the depression not being visible from the side.