Cut half-square triangle units quickly with this OMNIGRID right-triangle ruler for quilting, patchwork, and appliqué prep. It’s sized for finished blocks up to 8 in (20.3 cm) and the measurements include seam-allowance calculations so you can cut matching triangles from a strip with fewer steps. Use on a self-healing mat and keep the ruler flat and steady to maintain alignment from the first cut to the last.