OLO markers currently come in 128 colors and are an alcohol-based marker. They use a revolutionary ink cartridge technology and are customizable so that you can get only the tip you want and not be forced into a full-size pen with a tip that you rarely ever use. ScrappyShak offers the brush tip “half pen” which allows you to create a full-size pen with 2 different colors, saving you space and ink. No wasting of ink to a tip that you don’t need.