When sourcing multi-function showers, prioritize high-grade materials such as SUS304 stainless steel or solid brass to ensure corrosion resistance. Key technical specs include ceramic valve cartridges tested for at least 500,000 switching cycles to prevent leaks. For the spray functions, ensure the unit offers at least three modes: Rainfall, Massage, and Mist, with easy-to-clean silicone nozzles that prevent lime-scale buildup. Additionally, verify the surface treatment quality, such as a multi-layer electroplating process that passes a 24-hour Acid Salt Spray Test (ASS).