I use it on a lg marineland breeder box for some moss and pellia, and it fits perfectly on the side, so it is more than enough for me. The arm is not really flexible though. Not sure what you use it for, but spend a little more on a led fixture if this is for a tank and you intend to grow plants.
btw, I probably will not pay $15 for that but I got it for $5 from aokashi, thanks. The damn ripoff ice cream on a crepe cone cost me $5 dollars from an ice cream truck stopped by near my house a cpl months ago, so compare the 2 I would rather spend it on this led, lol.