1. These nice stuffs are head inserts used in most common tire changer mount / demount heads, the duck head shaped tire changing tool, making it easier to maneuver for you in mounting or unmounting your tire. The material of tire changer nylon insert rim protection kit for metal mount head duckhead is nylon plastic. 2. These nice stuffs are head inserts used in most common tire changer mount / demount heads, the duck head shaped tire changing tool, making it easier to maneuver for you in mounting or unmounting your tire. The material of tire changer nylon insert rim protection kit for metal mount head duckhead is nylon plastic. 3. Tire changer mount demount head inserts are found on the inside of the steel mount head and protect wheels from scraping and gouging due to the metal head ing the wheel. 4. Plastic heads insert for installing or uninstalling tires will also replace the metal roller that many of these machines came with originally. It is extremely easy to convert to nylon style insert from a steel roller. No modification is needed; simply unbolt the steel roller and bolt in the nylon insert.