power compact screw in 6500k bulbs at wal mart!

How much do they go for?
 
Width?

I found that on my 10 gallon tank, some of those bulbs only fit the hood that had no reflector. On the other one, I got the U-shaped tube 10 watt lights in the Walmart pet department.
 
Yes, I have one of those. I was looking for a 15watt, so I could get 3 watts per gallon, however, since my plants (java fern/moss) seem to be doing alright, I suppose I'll not need a higher wattage.
 
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