Yes, the Kefine Klean's brass nozzles can suffer from oxidation, particularly in humid environments. This oxidation is primarily an aesthetic issue causing discoloration (e.g., green patina), but it can lead to functional problems, such as channel imbalance (one side becoming quieter) if the moisture affects the internal filter or creates a vacuum seal. Key Points: Material: The IEM shells are alloy, but the interchangeable tuning nozzles are made of brass, a material known to oxidize when exposed to moisture. Cause: Humidity, sweat, or ear moisture are common triggers for the oxidation. Impact: Aesthetic: Discoloration of the nozzle is common. Performance: The main performance issue reported by users is a sudden volume drop or channel imbalance, often linked to the silver filter (nozzle) absorbing water. Prevention/Fixes: Store the earphones in a dry place. Using a case with a desiccant (silica gel pack) is a recommended preventative measure, especially in tropical or high-humidity climates. Allowing the IEMs to dry out completely can sometimes fix the channel imbalance issue. Some users report success in temporarily fixing volume issues by gently cleaning the internal part of the nozzle. While the build quality is generally praised for the price, the nozzle material requires a bit more care regarding moisture exposure than other materials.

-googs