Ultimaker - Silicone Nozzle Cover
Silicone Nozzle Cover for Ultimaker 3 and Ultimaker 3 Extended.
The nozzle cover shields the print cores from cold airflow from the fans, which helps the print cores to maintain a stable temperature while printing. The cover also helps to prevent backflow of material into the print head when something goes wrong during printing. The heat of the nozzles may cause wear on the nozzle cover over time. It is recommended to check the quality of the cover at least once every three months.