The SDCM (Standard Deviation of Colour Matching) measured value specifies the chromaticity locus stability of LEDs: this is important particularly for the operating duration of LED luminaires. The human eye is very sensitive to the colour differences in light sources. The lower the SDCM value, the tighter colour tolerance is. ERCO uses high-power LEDs with SDCM<2 (<3 up to 50,000h) to maintain their high quality, prestigious impression across the complete operating duration of the lighting installation. The animation illustrates the effect of chromaticity locus stability for 50,000 operating hours. ERCO luminaires with high-power LEDs with SDCM<3 for up to 50,000 operating hours (on left) display no significant colour differences. Luminaires with standard LEDs with SDCM<5 for up to 50,000 operating hours (on right) display clearly visible colour differences.