FLAT KEY PROFILE FOR A LOCK-KEY SYSTEM

The invention relates to a flat key profile for a lock-key system in which a keyway corresponding to the key profile is provided in the lock cylinder. Here, the key profile of the key shank has an upper profile portion facing the key spine and a lower profile portion facing the key breast, wherein a triangular paracentric profile groove (2) projecting beyond the centre plane of the key shank is provided in the lower profile portion in the one lateral surface of the key shank, a triangular profile groove (3; 4) arranged one above or one below the opposite paracentric profile groove (2) is provided on the opposite lateral surface of the key shank, and the arrangement of the paracentric profile groove in relation to the opposite profile grooves is such that an imaginary line (7), which runs perpendicularly to the key shank plane from the point of intersection of the upper or lower leg of the paracentric profile groove with the key lateral surface to the opposite profile groove, has a vertical spacing (9) from an imaginary line (5) which extends from the point of intersection of the upper or lower leg of the opposite profile groove with the key lateral surface to the paracentric profile groove.