We designed the limited-edition Blackwing Vol. 55 using the Fibonacci sequence, a series of numbers that approximate the value of the Golden Ratio. The width of each color block is the sum of the widths of the previous two. Each color section of the pencil is as follows: 1, 1, 2, 3, 5, 8, 13, 21, 34, & 55mm. Shop the Blackwing Vol. 55 at blackwing602.com now.