This ruler is designed to make it easy to cut finished half square triangles from two strips of fabric sewn together down each side (made into a tube). The Strip Tube Junior Ruler works in the same way as the original Strip Tube ruler but in a smaller size so it’s easier to use on smaller pieces. The Junior will help you make accurate half square triangles from 1″ to 6-1/2″! Instructions included. Used in some of the Cozy Quilt Designs patterns.