WARNING: Do not buy from SB Reef Lights. I have an 18" sBox Basic. The knob for the blue channel no longer adjusts the brightness, only off and on; it stays at the same brightness level no matter what. Also, both channels don't click on until about 12%. They supposedly have a 2 year warranty, but won't respond. I have sent multiple emails, left multiple voice messages over the last two weeks, and just recently tried contacting them through Facebook too, but haven't heard back. Save yourself the hassle and don't buy from them. Apparently they don't stand by their product.