An injection device for administering or delivering fluid product, preferably a pen-shaped injection device, comprising - a housing (5, 105, 205), - a delivery device comprising a piston rod, which is movable relative to the housing (5, 105, 205) in a delivery direction in order to dispense a set product dose, and a drive element (7, 107, 207), which is in engagement with the piston rod, - a dosing apparatus having a dosing sleeve (11, 111, 211) and a rotary knob, - the rotary knob being rotated in one direction during the dosing process and in the opposite direction during the dose correction, - a dispensing button (14, 114, 214) arranged coaxially on the dosing sleeve (11, 11, 211) and - a receptacle for the product, the dosing apparatus being able to be coupled to the delivery device via a coupling mechanism, - the coupling mechanism consisting of at least two coupling surfaces (10b, 11 0b, 11f) each having a toothing (10c, 110c, 115o, 115u, 210c, 11b, 111b) consisting of teeth, and - the at least two coupling surfaces (10b, 110b, 11f) being able to be brought into engagement by means of a spring (13, 113, 216), - the coupling surfaces (10b, 11f) during the dosing process and during dose correction serving to generate an acoustic and/or tactile signal according to the set or corrected dose of the product to be administered, and - wherein the relative movement between the at least two coupling surfaces (10b, 110b, 11f) being able to be prevented by triggering the dispensing button (14, 114, 214), characterized in that - the coupling mechanism has a coupling member (10, 110, 210), which is arranged non-rotatable but axially displaceable on the drive element (7, 107, 207), - one of the at least two coupling surfaces (10b, 110b, 11f) is rigidly attached to the coupling member (10, 110, 210), and - a further one of the at least two coupling surfaces (10b, 110b, 11f) is rigidly attached to the dosing sleeve (11, 111, 211), so that the coupling surface (10b, 110b of the coupling member (10, 110, 210) and the coupling surface of the dosing sleeve (11, 111, 211) can be brought directly or indirectly into a coupling engagement with one another, a back drive safety (7b, 117) being arranged between the housing (5, 105, 205) and the drive element (7, 107, 207), so that the drive element (7, 107, 207) can rotate only in the dispensing direction and a rotation of the drive element (7, 107, 207) counter to the dispensing direction will be blocked. - a housing (5, 105, 205), - a delivery device comprising a piston rod, which is movable relative to the housing (5, 105, 205) in a delivery direction in order to dispense a set product dose, and a drive element (7, 107, 207), which is in engagement with the piston rod, - a dosing apparatus having a dosing sleeve (11, 111, 211) and a rotary knob, - the rotary knob being rotated in one direction during the dosing process and in the opposite direction during the dose correction, - a dispensing button (14, 114, 214) arranged coaxially on the dosing sleeve (11, 11, 211) and - a receptacle for the product, - the coupling mechanism consisting of at least two coupling surfaces (10b, 11 0b, 11f) each having a toothing (10c, 110c, 115o, 115u, 210c, 11b, 111b) consisting of teeth, and - the at least two coupling surfaces (10b, 110b, 11f) being able to be brought into engagement by means of a spring (13, 113, 216), - the coupling surfaces (10b, 11f) during the dosing process and during dose correction serving to generate an acoustic and/or tactile signal according to the set or corrected dose of the product to be administered, and - wherein the relative movement between the at least two coupling surfaces (10b, 110b, 11f) being able to be prevented by triggering the dispensing button (14, 114, 214), - the coupling mechanism has a coupling member (10, 110, 210), which is arranged non-rotatable but axially displaceable on the drive element (7, 107, 207), - one of the at least two coupling surfaces (10b, 110b, 11f) is rigidly attached to the coupling member (10, 110, 210), and - a further one of the at least two coupling surfaces (10b, 110b, 11f) is rigidly attached to the dosing sleeve (11, 111, 211), so that the coupling surface (10b, 110b of the coupling member (10, 110, 210) and the coupling surface of the dosing sleeve (11, 111, 211) can be brought directly or indirectly into a coupling engagement with one another,