Many of those having diabetes take a combination of slow and fast acting types of insulin. It is important that the different forms of medicament do not become confused and that the patient does not receive the incorrect medicament. In combination a medicament delivery apparatus and a medicament cartridge are provided, the medicament delivery apparatus including at least one switch and the medicament cartridge comprising a cartridge housing 4 within which a medicament is provided, a displaceable piston 14 located internally at one en of the housing 4 and a raised ring 10 of material about an external periphery of the medicament cartridge, the ring 10 of material being of sufficient dimensions, in use, to trip the at least one switch of the medicament delivery apparatus.
