A large container essentially comprising an ISO frame in which liquid containers are mounted. They must meet special requirements with respect to pressure-resistance as a result of the pressures they have to withstand. For this reason, the actual containers are generally cylindrical or spherical in form. Several containers can be mounted either horizontally or vertically in a single frame. Only specific containers must be used for foodstuffs and must be marked "Potable liquids only". Tank containers for hazardous goods must meet the requirements of the IMDG code. Half-height tank containers serve to carry high-density liquids which cannot be carried in normal tank containers because they cannot be filled to a high enough level and are therefore subject to surging.