Using UltiMaker  cleaning filament is the most effective way to unclog and keep print cores and nozzles in optimal condition. When to use the Ultimaker cleaning filament The Ultimaker  cleaning filament is used for both print core maintenance and unclogging...
This is the filament guide assembly that sits on the back of the reel holder to prevent filament from tangling.
This is compatible with the following printers:
Ultimaker 3
Ultimaker 3 Extended
Ultimaker S5
Ultimaker S3
Ultimaker S7