I use Sylvania gro-lux 4' bulbs over my growchamber. I had to do an internet search for the CRI and Kelvin ratings. According to several websites that sell them, their CRI is 89, and color temperature is 3400K, which is considerably lower than what is usually recommended. The 3400K does seem to match the color of the light output, thought, which is purplish, when you look right at the bulb. Nevertheless, the plants in the grow chamber are doing very well under them. The neps and dews, etc. are doing great, and I kept my vfts in there before I put them outside in mini bogs, and they put up flower stalks(or tried to anyway, I cut them off) and the traps were nice and red.