Specialized transport is an important sub-sector of the global freight and transport industry, and covers the transport of very heavy, large or unusual items, often using specially designed equipment such as low-loaders, SPMT (self-propelled modular transporter) and offshore transporters. It is a sector that is particularly active in infrastructure, oil and gas, petrochems and energy – including wind turbines – where specialist transport contractors move items such as turbine blades, process units or offshore modules.