Discover Gravity Blox, the gravity-defying stacking toy! Ready to learn the secret behind these amazing blocks? Hidden weights! Orange blocks are weighted on one end, green blocks are weighted in the middle, and gray blocks have no weight at all. Knowing the location of the weight allows you to stack the blocks in ways that appear to be impossible. Amaze your family and friends! Includes an idea booklet that illustrates over 30 gravity-defying shapes to build. Try them, then create your own! Set contains 4 each of orange, green and gray blocks. For ages 4 and up.