NilfiskCFM 50mm continuous suction nozzle. It's also available in 40mm SKU  and 70mm SKU 

This is for vacuuming large heaps of material, such as mineral sands, grain, gravel. etc. It allows air to pass with the product, as otherwise the hose can become blocked, especially when using long lengths.

See the second photo for an example of it being used with ballast with the Spirovac machine.

Probably most suited to the and the and the and the industrial vacuum cleaners using 50mm hosing, as well as the

At the moment standard postage within Australia, is capped at a maximum of $25, so maximise the saving on postage and buy something in related items below!