Multiple service vertical distribution module, constructed from primed or galvanised mild steel and incorporating appropriate building services which may or may not be lagged (insulated). These modules can be connected offsite, but are often transported in 7.5m lengths to avoid transportation problems. Modules can carry combined mechanical and electrical services but most manufacturers specialised in one or the other. The majority of the electrical risers are manufactured using a mesh or ladder system to allow easy distribution at floor levels in various directions. These systems are often bespoke in design and while the base structure may offer a level of standardisation the dimensions are carrying capacity will vary between projects.