So if you've been following the thread you will know I know very little about these, thanks for the suggestion of these two, Can you explain why? The kit I ordered above will give a great assortment for playing with and experimenting so no regrets on that but I'm sure I'm missing something regarding this project and what I'm looking to do. Since you pointed out some specs I got looking at my list and I see Response Time Rose and Drop - .6(min). Does that mean 36secs for a full rise AND drop or 16 secs for a full rise OR drop? I see the LDR you listed is $11.50 so is response time and light sensitivity a lot better?