What does SUS 304 mean

SUS 304 is the designation for 304 stainless steel in the Japanese Industrial Standard (JIS G4303):
SUS is the Japanese stainless steel code, 304 corresponds to the internationally recognized austenitic stainless steel grade, and the core components are chromium (18% -20%) and nickel (8% -10.5%).

Its performance and application are equivalent to the international standard 304 stainless steel:
SUS 304 steel has excellent corrosion resistance, formability, and weldability, and is widely used in food equipment, medical devices, building structures, etc. It is not a material unique to Japan.