Don Rankin's Magic Value and View Finder has a complete value scale with open holes for isolated comparison of different colors. It also has a typical open view finder window that is of the most common format for most paintings. In addition to the value scale and viewfinder, this "Perception Kit" includes a red neutralizing piece that may be used alone or placed behind the tool to make finding values even easier.
Just follow the simple instructions and watch your paintings and drawing improve.
Note - Be careful not to throw away the red neutralizing piece. It is covered with brown protective paper to keep it from being scratched in shipping. We have added a sticker stating “Don’t throw me away!” to remind you.