This is a bid for 13mm internal diameter (16mm outside diameter) pipe. If you are not sure it is the correct pipe to buy try the 4" sample. This pipe is for use with all standard automatic watering by Hozelock or Gardena which pipe is compatible with all 13mm irrigation connectors.The maximum length we sell is 100m,longer lengths will be sent as multiples of 100m. Any further inquiries regarding this or other products;