Half-Square Triangle Ruler Set #2 contains 2 1/2", 4 1/2" and 6 1/2" multiple sized rulers. Each ruler locks onto the seam for instant ruler placement and control so that the seam ends in each corner. Trims 90% faster than a flat ruler and ruler rock is gone, too. Also trims quarter-square triangles, birds in the air, y-units, LeMoyne Star, double windmill, hidden squares units and much, much more! Trims in 1/8" increments.