For example, the one shown here is a very popular twin cabinet type with a central upright divider panel extending into the lid. The usual layout of the speaker trunk is that the cabinets face each other in the case, with the grilles up against the divider. This protects the grille and drivers whilst in transit. All speaker trunks are lined with a combination of polyethylene and polyester foam, to ensure protection.
Very often and especially with shaped ‘trapezoid’ type cabinets, the base foam is shaped to suit the cabinet’s profile. Also, with a Top-Hat style trunk the low base makes removal of the cabinets much easier, rather than lifting the speaker over a deep base.