TammyLiz, my Dollar Tree had two different sets. One set comes with two red, two blue, and two white. The other set is all black. I bought one of each set thinking that I might use the colored ones. However, I ended up using the black ones because it matched the black plastic on the tank. I think they are much harder than the ones at other stores, but it really worked as an advantage. They hold the canvas very tight.
Oh, thank you! I wish I had heard of this before I made my dividers. I was looking everywhere with a pack of all black, and couldn't find one! Plus, it's cheaper! Ahh! Well, I ended up doing white which looks OK but black would have been nicer. I just didn't want the multicolor, so I ended up buying a 50 pack. There's no way I'm ever going to need any more, I've only used nine.