Well cheezy im not an expert either but i do read alot. The "K" is just Kelvin meaning the color temperature of the bulb. It doesnt mean the bulb is actually 2700 Kelvin it just means it is the degree of warmth or coolness of a light source, not with regards to the physical temperature, rather to the visual temperature of the light. The higher the degree K, the more blue or "cooler the lamp appears. The lower the degree K, the more "warm", or red the light appears. From my understand, photosynthesis takes place more efficiently during vegitation under 6500K or daylight. And the same for 2700K during Flowering. I don't know why, my friend thats just the way it is.