When sourcing toilet fittings, prioritize material durability and water efficiency. For fill and flush valves, ensure they are made of high-grade ABS or POM plastics to resist corrosion and mineral buildup. Look for dual-flush mechanisms that offer adjustable water volumes (e.g., 3L/6L) to meet water-saving standards like LEED or WaterSense. Additionally, verify that the critical dimensions, such as the shank size (typically 15mm or 20mm) and overflow pipe height, are compatible with your specific toilet tank models.