4 x 24 watt I believe he is talking about, 24" long
I have one on my frag tank, a 20 gallon high, and it is working mint!! Actually too good I have to start all my corals on the bottom and work up because it is strong and i have a FishNeedIt t5 fixture, so nothing special! I am keeping LPS mainly with some shrooms, but on my top rack i could keep sps if i kept the tank cleaner, and did more water changes.