Several designs of a reducer nozzle, 7 to 1mm, and an angled joiner reducer, 7 to 4mm, for a University Project for an Unmanned Firefighting vehicle.
Threaded reducer nozzles are made for M4/5 Irrigation Nozzles.
Long Nozzles are approx. 28mm without the threaded insert.
Short Nozzles are approx. 7.5mm without the threaded insert.
The author hasn't provided the model origin yet.