You know I was thinking the other day when I was in Michaels standing in line right where they have the Copic markers that I needed an app for my markers. I wouldn't buy them at Michaels, but its a pain to try and find the chart I've coloured in with which markers I have. I always know where my phone is, so that would be sooooo much more convenient. And if I'm out and about, I always have my phone with me, so if I do happen to run into a good sale, then I'm prepared and know which ones to get. I have been known to order doubles and triples of colours I like.