Extra Heavy Duty Extension Lead:

For indoor, outdoor and harsh environments.
The extra heavy-duty lead has a larger diameter cable and longer maximum allowable length from the outlet to the appliance than heavy-duty leads.
It is suitable for use on sites with a few 3-phase outlets, or the lead is connected to a temporary site power board that is a long way from the local distribution board, where voltage drop is a consideration (either the machine is a considerable distance from the main distribution board or has high starting current).