The "ID" type nozzle is known as “universal”, because thanks to its cone shape can be inserted at the end of a tube and each nozzle is able to fit the different diameters inside a given range.

The correct nozzle is chosen according to the internal diameter of the tube.

The "OD" type nozzle interfaces with the tube in the opposite way of the ID type. In this case it’s the tube that is introduced inside the nozzle and the diameter must be precise.

The correct nozzle in this case is chosen according to the external diameter of the tube.