Disclosed herein are cartridge assemblies that include coding features that help dedicate a medicament reservoir to specific injection devices. An exemplary cartridge assembly comprises a cylindrical inner surface for holding medicament and a cylindrical outer surface comprising at its proximal end one or more stops configured as coding elements protruding from the cylindrical outer surface. Each coding element is configured only to engage a corresponding coding feature on a dose setting and delivery mechanism, thereby allowing only the correct cartridge assembly to connect to the dose setting and delivery mechanism.