- May have arrangements for either gravity or pressure discharge
- Frame constructed as several hoppers within an ISO framework
- Some of tank type.
- Some may have full size doors at one end and a smaller discharge hatch at the other.
- Filling hatches (2 or 3) are set in the roof.
- Some have provision for aeration or vibration to assist discharge
- Suitable cargo includes free flowing solid cargoes (eg granules, powders, grains)