FLAT KEY PROFILE FOR LOCK-KEY SYSTEM

Flat key profile for lock-key system, wherein keyway corresponding to key profile is provided in lock cylinder. Here, key shank profile has upper profile portion facing key spine and lower profile portion facing key breast, wherein triangular paracentric profile groove (2) projecting beyond centre plane of key shank is provided in lower profile portion in one lateral surface of key shank, triangular profile groove (3; 4) arranged one above or one below opposite paracentric profile groove (2) is provided on opposite lateral surface of key shank, and the arrangement of paracentric profile groove in relation to opposite profile grooves is such that imaginary line (7) running perpendicularly to key shank plane from the point of intersection of upper or lower leg of paracentric profile groove with key lateral surface to opposite profile groove has vertical spacing (9) from imaginary line (5) extending from the point of intersection of upper or lower leg of opposite profile groove with key lateral surface to paracentric profile groove. Paracentric profile groove (2) has at least one stage (13) on upper angle or at least one stage (12) - on lower angle. s