The present invention provides test or training a cartridge for a drug delivery device as well as a method for resetting of such cartridge, wherein the cartridge comprises: a body of substantially cylindrical shape, a piston slidably disposed in the body in an axial direction, a closure means disposed at an axial end portion of the body, wherein the body, the piston and the closure means confine an interior volume coupled to the exterior via at least one fluid escape channel.
