Hey gromies. My friend is sending me a cmh bulb for free. It has no box or label. all I know is that it is a 315w. And it came with a sun system 315w vertical fixture. Does anyone know how to tell what spectrum bulb it is just by looking at the bulb itself? Is there a physical difference between 3k, 4k, 10k etc bulbs? I seen it over FaceTime so I can't post a pic yet. But it's coming in mail anyday now and I will post the pic asap. I tried to Google it but came up short. Any help would be appreciated. Thanks everyone!