Materials: Our metal nozzles are made of copper alloy. The nozzle helps prevent stains on fingers and may reduce the intake of certain substances during use. Filtration principle: A pull rod filter is installed inside the nozzle. As smoke passes through the filter's dual channels, it comes into contact with the internal surfaces, promoting condensation and deposition of certain components through a physical filtration process. Cleaning the filter: Empty the small bore of the filter regularly. Slowly pull the lever to avoid splashing, and wipe away residue with a paper towel. Small holes in the filter rod can be cleared using a needle if needed. Note: The filter typically requires cleaning after 5–10 uses. Due to the smooth inner surface, optimal performance may be reached after 10–20 uses. If unused for several days, the lever may become stiff. In such cases, soaking the filter in hot water for 5–10 minutes may help restore function.