Patent ID: 6912881

Claim:
A security reversible-key with at least three coding pin rows (A 1 , A 2 , A 3 ) located on flat sides of the key (S), with an assigned cylinder (Z) with tumbler pin rows of pairs of tumbler pins, said tumbler pin pairs consisting of tumbler pins and counter pins at the positions of the coding pin rows of a given bore pattern, wherein: the key has a blocking groove (BN) in a coding pin row (A 1 , A 2 ) that runs parallel to an axis (x) of the key from a tip of the key to at least a first coding position (P 1 ) of the coding pin row on the key, the blocking groove has a coded blocking depth (B 1 , B 2 , B 3 ) and, in the assigned cylinder at least at a rearmost coding position (P 1 ′), a pair of blocking tumbler pins corresponding to the blocking groove (BN) with a blocking tumbler pin (BZ) and an extended blocking counter pin (BG) are received, wherein a total length (lb) of the blocking tumbler pin (BZ) and the blocking counter pin (BG) is almost equal to a distance (db) from the blocking groove (BN) to a cylinder housing ( 10 ), so that the blocking counter pin impinges on the cylinder housing ( 10 ) if the blocking groove is not deep enough and complete insertion of a key with an insufficiently deep blocking groove is blocked by the pair of blocking tumbler pins and whereby the blocking tumbler pin (BZ) together with the blocking counter pin (BG), following insertion of the key at the first coding position (P 1 ) on the key, is also utilized as a coding tumbler pin with coding steps (C 1 , C 2 , C 3 , C 4 ) for turning of the cylinder.