A system comprising: a set of containers (100, 202, 302, 702, 802, 902, 1002, 1102) for storing therein a liquid drug substance or other pharmaceutical solution which is to be frozen and thawed, with each of the containers (100, 202, 302, 702, 802, 902, 1002, 1102) in the set having an essentially parallelepiped configuration with a substance-receiving cavity defined therein by the walls (104, 304, 832, 834) of the container (100, 202, 302, 702, 802, 902, 1002, 1102); wherein each of the containers (100, 202, 302, 702, 802, 902, 1002, 1102) in the set has a pair of major walls on opposite sides of the container that define a length and a height of the respective container, the major walls of each of the containers (100, 202, 302, 702, 802, 902, 1002, 1102) being spaced apart by a distance that defines a width of the respective container (100, 202, 302, 702, 802, 902, 1002, 1102); wherein the substance-receiving cavity of at least one of the containers (100, 202, 302, 702, 802, 902, 1002, 1102) in the set has a first volume and the substance-receiving cavity of at least another one of the containers (100, 202, 302, 702, 802, 902, 1002, 1102) in the set has a second volume, which is different from the first volume; and wherein all of the containers (100, 202, 302, 702, 802, 902, 1002, 1102) in the set have the same width, such that a freeze-path length associated with each of the containers (100, 202, 302, 702, 802, 902, 1002, 1102) in the set is essentially the same, wherein the set of containers comprises: a first container; and a plurality of second containers; characterised in that the system comprises a cassette, wherein the second containers are secured together by the cassette to form a group of containers, the group of containers having essentially the same length and height as the first container. a set of containers (100, 202, 302, 702, 802, 902, 1002, 1102) for storing therein a liquid drug substance or other pharmaceutical solution which is to be frozen and thawed, with each of the containers (100, 202, 302, 702, 802, 902, 1002, 1102) in the set having an essentially parallelepiped configuration with a substance-receiving cavity defined therein by the walls (104, 304, 832, 834) of the container (100, 202, 302, 702, 802, 902, 1002, 1102); wherein each of the containers (100, 202, 302, 702, 802, 902, 1002, 1102) in the set has a pair of major walls on opposite sides of the container that define a length and a height of the respective container, the major walls of each of the containers (100, 202, 302, 702, 802, 902, 1002, 1102) being spaced apart by a distance that defines a width of the respective container (100, 202, 302, 702, 802, 902, 1002, 1102); wherein the substance-receiving cavity of at least one of the containers (100, 202, 302, 702, 802, 902, 1002, 1102) in the set has a first volume and the substance-receiving cavity of at least another one of the containers (100, 202, 302, 702, 802, 902, 1002, 1102) in the set has a second volume, which is different from the first volume; and wherein all of the containers (100, 202, 302, 702, 802, 902, 1002, 1102) in the set have the same width, such that a freeze-path length associated with each of the containers (100, 202, 302, 702, 802, 902, 1002, 1102) in the set is essentially the same, wherein the set of containers comprises: a first container; and a plurality of second containers; characterised in that the system comprises a cassette, wherein the second containers are secured together by the cassette to form a group of containers, the group of containers having essentially the same length and height as the first container. a first container; and a plurality of second containers; characterised in that the system comprises a cassette, wherein the second containers are secured together by the cassette to form a group of containers, the group of containers having essentially the same length and height as the first container.