Some of my favorite brush pens are the Tombow Dual Brush Pens - In the button above find a guide on the current available sets, and what colors are in each of those sets. The guide has recently been update to include the new 20 Brush Pen sets. Tombow actually has a great paper tracker to notate which pens you own, this guide is mostly geared to people who need to build up a collection or need to replace certain colors. Mostly it will allow you to see what colors are repeated in which sets, and which colors you cannot find in any sets. Enjoy!