The Printing Head is a removable extruder, just like any extruder of a 3D printer is composed by an heatsink and a melting chamber.
The heatsink (also called “cold end”) is where the filament is kept solid until in the melting chamber. In the cold end temperature must be as low as possible, especially when 3D printing materials like PLA, which would easily melt and block the path toward the melting chamber.
To avoid that a small built-in fan is always keeping the heatsink at lower temperatures than the “hot end” or the melting chamber.
The Printing Head has dual cooling to keep the temperatures in check.
On the hot end side the most important part is the nozzle: this last component heats up and deposit the material in thin layers. Here there will be a thermistor and a resistance: the first one will detect the temperature and send the value to the board to record it, the second one will increase or decrease the read value in order to get the needed one when printing.
The Printing Head can be serviced and different nozzles and thermistors be swapped when worn out or too old.
Nozzles can also have different diameters. The Printing Head comes with a 0,4mm hole, while 0,6mm is available separately.