A metering device for dispensing defined doses of a flowable material (12a, 12b), comprising two cylindrical bodies (14a, 14b) with their interior space respectively defining a cavity for taking up the flowable material (12a, 12b), wherein each cylindrical body (14a, 14b) comprises a first open end (16a, 16b) and a dispensing opening (18a, 18b) opposite thereto, the metering device further comprising: two pistons (20a, 20b) for axial insertion into said first open end (16a, 16b) of a cylindrical body (14a, 14b) in a manner causing the flowable material (12a, 12b) to be displaced by the pistons (20a, 20b) and to be pressed out of the dispensing openings (18a, 18b), characterized in that each cylindrical body (14a, 14b) comprises elements for guaranteeing that, with each operating step, the piston can be advanced into the cylindrical body (14a, 14b) by a defined amount so that a defined dose of the flowable material (12a, 12b) is dispensed through the dispensing openings (18a, 18b) of the cylindrical bodies (14a, 14b), wherein, for this purpose, the metering device comprises, in each piston (20a, 20b), abutment elements (22a to 22g) adapted to be radially pressed in, said abutment elements being arranged at an axial distance to each other, wherein an abutment element in its non-pressed-in state extends, in the radial direction, beyond the inner diameter (i) of the cylindrical body and thus forms an abutment for the respective edge (24a, 24b) of the cylindrical body (14a, 14b) surrounding its open end (16a, 16b) in such a manner the piston (20a, 20b) cannot be inserted into the cylindrical body (14a, 14b) beyond said abutment, and an abutment element in its pressed-in state does not extend, in the radial direction, beyond the inner diameter (i) of the cylindrical body, thus allowing the piston to be inserted into the cylindrical body beyond said abutment element, the abutment elements (22a, 22c, 22e, 22g) of the first piston have an identical distance to each other in the axial direction, the abutment elements (22b, 22d, 22f) of the second piston have an identical distance to each other in the axial direction, wherein the distance between two adjacent abutment elements (22a, 22c) of the first piston or of the second piston multiplied by the cross-sectional area of the respective piston results in twice the volume to be dispensed by the metering device as a dose, wherein the abutment elements (22a, 22c, 22e, 22g) of the first piston are offset relative to the abutment elements (22b, 22d, 22f) of the second piston in the axial direction by a distance which corresponds to half the distance between two adjacent abutment elements of the first or the second piston (20a, 20b). comprising two cylindrical bodies (14a, 14b) with their interior space respectively defining a cavity for taking up the flowable material (12a, 12b), wherein each cylindrical body (14a, 14b) comprises a first open end (16a, 16b) and a dispensing opening (18a, 18b) opposite thereto, the metering device further comprising: two pistons (20a, 20b) for axial insertion into said first open end (16a, 16b) of a cylindrical body (14a, 14b) in a manner causing the flowable material (12a, 12b) to be displaced by the pistons (20a, 20b) and to be pressed out of the dispensing openings (18a, 18b), characterized in that each cylindrical body (14a, 14b) comprises elements for guaranteeing that, with each operating step, the piston can be advanced into the cylindrical body (14a, 14b) by a defined amount so that a defined dose of the flowable material (12a, 12b) is dispensed through the dispensing openings (18a, 18b) of the cylindrical bodies (14a, 14b), wherein, for this purpose, the metering device comprises, in each piston (20a, 20b), abutment elements (22a to 22g) adapted to be radially pressed in, said abutment elements being arranged at an axial distance to each other, wherein an abutment element in its non-pressed-in state extends, in the radial direction, beyond the inner diameter (i) of the cylindrical body and thus forms an abutment for the respective edge (24a, 24b) of the cylindrical body (14a, 14b) surrounding its open end (16a, 16b) in such a manner the piston (20a, 20b) cannot be inserted into the cylindrical body (14a, 14b) beyond said abutment, and an abutment element in its pressed-in state does not extend, in the radial direction, beyond the inner diameter (i) of the cylindrical body, thus allowing the piston to be inserted into the cylindrical body beyond said abutment element, the abutment elements (22a, 22c, 22e, 22g) of the first piston have an identical distance to each other in the axial direction, the abutment elements (22b, 22d, 22f) of the second piston have an identical distance to each other in the axial direction, wherein the distance between two adjacent abutment elements (22a, 22c) of the first piston or of the second piston multiplied by the cross-sectional area of the respective piston results in twice the volume to be dispensed by the metering device as a dose, wherein the abutment elements (22a, 22c, 22e, 22g) of the first piston are offset relative to the abutment elements (22b, 22d, 22f) of the second piston in the axial direction by a distance which corresponds to half the distance between two adjacent abutment elements of the first or the second piston (20a, 20b).