The invention concerns a device (1) for moving the piston inside a cartridge. It comprises a first portion (4) having first coupling means (5) for releaseably coupling the cartridge body (2) of the cartridge to the first portion (4) of the cartridge body (2) and a second portion (6) having second coupling means (7, 11a, 11b, 12 7, 12, 17a, 17b) for releasably coupling the piston (3) of the cartridge to the second portion (6). Said first (4) and second portions (6) are moveable relative to each other in order to effect, in the intended use of the device (1), at least a forward displacement of the piston (3) inside the cartridge body (2) along the longitudinal axis (Z) of the cartridge body (2). The second coupling means (7, 11a, 11b, 12 7, 12, 17a, 17b) are designed in such a manner that for establishing and releasing the connection with the piston (3), their shape can reversibly be changed. By this design it becomes possible to generate a system comprising the device and a dedicated cartridge wherein the cartridge can be of a simple, inexpensive design, thus making the system attractive for use in fields where the cartridge should be an inexpensive single use article, like e.g. for use as a system for filling self filled insulin cartridges.
