Katie Fowler's color tool makes it easy to see the colors in a variety of no-fail color schemes. The color wheel itself is pretty basic, 12-wedges of color. 

What sets it apart is that the set has 10 die-cut “discs” that float on a spindle over the color wheel to mask out the colors not in that particular color scheme. 

AND even better, this tool works very well with my own book, The Quilter's Practical Guide to Color!

• Pick color combinations that work together effortlessly
• Expand your knowledge of color relationships
• Choose from ten color schemes: direct complement, triadic, split complementary, tetradic, double complementary, double double complementary, double split complementary, double triadic, color sextet, and analogous