A dual vial 800 has an inner vial 810 nested inside an outer vial 820. A portion of the dual vial forming part of both the vials is a single continuous piece of material. The vials may be made complete by joining this piece with separate closing pieces, or they may be heat sealed. A method of packing the dual vial involves providing a first component into the outer vial, providing a second component into the inner vial, and closing both vials. The inner vial may be broken from the outer one to mix the components without breaking the outer vial, by operating a cap having a protrusion which contacts the base of the inner vial. A break zone 811 may be formed in a wall 812 of the inner vial by ultra-high frequency laser filamentation； preferably this zone is adjacent the transition zone 830 where the walls of the two vials converge.
