This unique ruler is perfect for squaring up or centering traditional quilt blocks, appliqué blocks and machine embroidered blocks and features the unique Non-Slip Coating. The inner area of the ruler has a 6-1/2" x 6-1/2" opening with measurement markings from center out. The outer edge measures 8-1/2" x 8-1//2" with traditional left to right measurement markings. All measurements in 1/4 in increments.