All the box stores sell them, and they do work well. What I have found with viewing most when I was purchasing (as I do have them under kitchen cabinets) was that if they came in a 16 foot roll, it would be 4 4' pieces and you have to click them together. (These were the ones at big box stores)
I went to an electrical supplier on Wellington by 401, I think it was called HD electrical supply or something, and they had them in 25' lengths, all one piece that just connected to the IR controller box, came with wireless remote. I'm not sure what the others have on the back of them, but these contained the really good 3M sticky tape that you just peeled a layer off and stuck it on.
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