With this ruler cutting pyramid shapes (Equilateral Triangles) is a snap. All the math is done for you. The Fons & Porter Pyramid Ruler is designed to cut finished triangles from 1in to 6in tall. Simply cut a fabric strip, then cut the equilateral triangles from the strip using the marked lines on the ruler that correspond to your finished block size. Each side of this template measures 7-7/8in. Center line measures 6.5in. Also included is an instruction sheet with detailed photography and design suggestions.