Here is a set i have. I used a quantum PAR and lux meter to read output and it is pretty even through out the four foot length of my fixture. My fixture is using 4 X "250" watt 8U CFL's. I say "250" watt because when i take an current reading it only draws 4 amps @ 115 volts or 460 watts not 1000! It seems the cfl's are drawing far less power than what they are advertised as. When you look at a 8U bulb , the tubes are actually T5 tubes and if you measure these tubes, it would stretch out to almost 15 feet of tubing all in a compact package. T5 simply means 5/8 in diam tube. 15 ft of standard T5 not HO works out to about the same wattage as one of these 8U's. As for the readings im getting a consistent 600 uMol/s at 18" above over an entire 4X3 ft area. i'm going to do a comparison with 1000 watt HPS and see how it compares but 600uMol/s is very good for any kind of lighting.