Get the cobs available from www.cobshop.net. I have 4 of the 3500K (very good veg to flower) in my 4x4 tent. I like them far better than the many mass built led lights I used for the years previous to cob lights. They are noise free. Low heat. Low electrical draw. Small, making them easy to move around. And highly efficient. But the best part of the cob lights is their positive affect on my plants health. Cobs rock.