When sourcing water-saving showers, the primary metric is the flow rate, typically measured in GPM (Gallons Per Minute) or LPM (Liters Per Minute). High-efficiency models should offer a flow rate of 1.5 to 1.8 GPM, compared to the standard 2.5 GPM. Additionally, prioritize Air-Injection Technology, which mixes air with water to maintain high pressure while using less water. Ensure the material is Lead-Free Brass or High-Grade ABS with Chrome Plating for durability and corrosion resistance. For maintenance, look for Self-Cleaning Silicone Nozzles that prevent limescale buildup.