Dear Sir, I am a senior project engineer. We have a swimming pool cleaner, which is always in the pool. From the cleaner, there is a stainless steel pin. The pin always touches water. Customer would like to use SUS303. Unfortunately, there is no SUS303 in the market at this moment. We then propose SUS303Cu, which is one of the variations of SUS303 from Japanese manufacturer. The main difference between SUS303Cu and SUS303 is copper element. SUS303Cu comprise 1.5%7E3.5% copper. Customer said that SUS303Cu does not suitable for the application. Chloride will attack copper. Rust problem will happen. Under that application environment, corrosion resistance of SUS303 is better than SUS303Cu. Is that true? Can you please advice? I am looking forward to receiving your professional response (if possible today). Many thanks. Regards, Tom.