These cases will keep your nozzle clean and free of burnt on blackened plastic. These also offer a huge boost in temperature stability, particularly if you use high airflow cooling around the nozzle to cool the print. Made of a heat-resistant, non-stick silicone material, rather than molten plastic.This really helps with sticky materials like Co-Polyesters and filled materials that like to build up on nozzles. Anti-high tempature for PLA/ABS 3D printing