(05/03/2008) - Ahhhh, what a great bulb. This is one of the best kept secrets for small to medium sized tanks. The pendant it is used on is very compact and packs a PUNCH with this bulb. The picture above doesnt show it but this bulb is essentially, a double ended hqi bulb with built-in mini reflectors INSIDE the outer bulb envelope. In otherwords, there is a mini, double ended bulb INSIDE the bulb pictured above. There are also reflectors INSIDE the bulb pictured above. This puts the reflective material really close to the light source and results in a great light spread (about 20x20 at 10" off the surface), while still keeping the size of the bulb and pendant very compact. The bulb is labeled as a "20K" but is more like a true 14K in color. Although 150watts, to my eyes, it looks brighter than a single ended Aqualine Bushke 13K bulb i'm also using. It is also a lot more blue than the 13K AB bulb. I HIGHLY recommend this bulb. The 6.5k bulb is also a great bulb especailly for refugiums. The 70watt, 6.5K bulb on Ice Cap pendant will make completely flood your refugium with light and make the macro algea explode :) Hope this helps.