The inner size of a VGK is 13700mm x 2650mm x 2701mm (LxWxH) which gives a total loading volume of 98 m3. The trailer has a door that's 2000mm x 2300mm (WxH).
A VGK has a default maximum payload of 68000kg. Depending on your use case or specific trailer this might vary and is easy to change.
Every aspect of the trailer, from lengths to axle count & weights, is of course customizable in Cargo-Planner.