Longitudinal adjuster for a vehicle seat, having - at least one lower rail, - at least one upper rail which is displaceable in a longitudinal direction (x) with respect to the lower rail, and - at least one locking unit for locking the upper rail with respect to the lower rail, wherein the locking unit comprises at least two locking mechanisms which, in order to lock the upper rail and the lower rail, engage therein in a stepwise locking manner such that - in a pre-locking step, at least one of the locking mechanisms pre-locks the upper rail and the lower rail to one another with play, and - in a locking step, at least one of the locking mechanisms locks the upper rail and the lower rail to one another in a play-free manner, characterized in that - one locking mechanism has a multiplicity of latching teeth (17b, 17b', 19b, 19b') and is configured such that one of the latching teeth (17b', 19b') is wider than all of the other latching teeth (17b, 19b), - the lower rail has a multiplicity of formations spaced apart at equal distances, wherein each formation has a protrusion, a web and a catch, - the catch is configured in a conical manner at its flanks (F1, F2) such that only the wide latching tooth (17b', 19b') of one of the locking mechanisms latches without play, - the upper rail is provided with a number of recesses (11a, 11a', 11a") which corresponds to the number of latching teeth (17b, 17b', 19b, 19b') of the locking mechanisms, - the upper rail has a number of recesses (11a, 11a', 11a'') in mutually opposite side walls per locking mechanism, wherein the recesses in one side wall are identical and the recesses (11a, 11a', 11a") in the opposite side wall differ at least in one parameter, - the locking element (17, 19) is configured as a latching plate with latching teeth (17b, 17b', 19b, 19b') which are arranged one behind another in the longitudinal direction (x) on both longitudinal edges and are arranged so as to be movable in the locking direction (z) in corresponding recesses (11a, 11a', 11a'') of the upper rail, - the upper rail has, per locking mechanism, at least one recess that is wider in the longitudinal direction (x) than the other recesses (11a, 11a'') and is configured as a receptacle for the wide latching tooth (17b', 19b'), and - the upper rail has, per locking mechanism, a recess which, in contrast to the other recesses (11a, 11a') is configured in a conical manner. - at least one lower rail, - at least one upper rail which is displaceable in a longitudinal direction (x) with respect to the lower rail, and - at least one locking unit for locking the upper rail with respect to the lower rail, wherein the locking unit comprises at least two locking mechanisms which, in order to lock the upper rail and the lower rail, engage therein in a stepwise locking manner such that wherein the locking unit comprises at least two locking mechanisms which, in order to lock the upper rail and the lower rail, engage therein in a stepwise locking manner such that - in a pre-locking step, at least one of the locking mechanisms pre-locks the upper rail and the lower rail to one another with play, and - in a locking step, at least one of the locking mechanisms locks the upper rail and the lower rail to one another in a play-free manner, characterized in that - one locking mechanism has a multiplicity of latching teeth (17b, 17b', 19b, 19b') and is configured such that one of the latching teeth (17b', 19b') is wider than all of the other latching teeth (17b, 19b), - the lower rail has a multiplicity of formations spaced apart at equal distances, wherein each formation has a protrusion, a web and a catch, - the catch is configured in a conical manner at its flanks (F1, F2) such that only the wide latching tooth (17b', 19b') of one of the locking mechanisms latches without play, - the upper rail is provided with a number of recesses (11a, 11a', 11a") which corresponds to the number of latching teeth (17b, 17b', 19b, 19b') of the locking mechanisms, - the upper rail has a number of recesses (11a, 11a', 11a'') in mutually opposite side walls per locking mechanism, wherein the recesses in one side wall are identical and the recesses (11a, 11a', 11a") in the opposite side wall differ at least in one parameter, - the locking element (17, 19) is configured as a latching plate with latching teeth (17b, 17b', 19b, 19b') which are arranged one behind another in the longitudinal direction (x) on both longitudinal edges and are arranged so as to be movable in the locking direction (z) in corresponding recesses (11a, 11a', 11a'') of the upper rail, - the upper rail has, per locking mechanism, at least one recess that is wider in the longitudinal direction (x) than the other recesses (11a, 11a'') and is configured as a receptacle for the wide latching tooth (17b', 19b'), and - the upper rail has, per locking mechanism, a recess which, in contrast to the other recesses (11a, 11a') is configured in a conical manner.