An adaptor top for a medicament cartridge, the medicament cartridge including a cylinder having a main body portion, a neck portion at a first end having a radially outwardly directed flange portion, a narrowing shoulder portion connecting the body portion and the neck portion, a cap beaded across the first end thereby to retain a fluid impermeable membrane, and the adaptor top comprising a first cylindrical body portion having a radially inwardly directed flange at one end, in use to be seated over and against the cap and a second cylindrical skirt portion being adapted, in use, to be seated against the shoulder portion of the cartridge, the second skirt portion including a plurality of fingers, the free ends of the fingers in use being adapted to be seated beneath the outwardly directed flange of the medicament cartridge.