White light has different shades: warm white light for LEDs has a value of 2500K-4000K on the color temperature scale, pure white 4000K-5000K and cold white 5000K-10.000K.
Nichia warm white LEDs just out of the production line can have a color temperature between 2580K and 4260K. If they would be directly integrated into strips or luminaries they will yield color inconsistent products that are generally unusable.
To overcome this problem, Nichia LEDs are color sorted, grouped in batches known as "Chromaticity Bins". Nichia, groups white LEDs in many Bins, thus allowing very good control of the white light color of your project.
The Nichia Bins for new generation LEDs start with the letters "sm" followed by a series of numbers, where the first two describe the color temperature (65 as in 6500K) while the last two narrow down the selection interval.