Bloc Loc Half Square Triangle Ruler 1.5 Inch - HST 1-1/2Half Square Triangle Ruler 1 1 2" x 1 1 2" 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. Also trims quarter square triangles, birds in the air, y units, LeMoyne Star, double windmill, hidden squares and much, much more! Multiple sized ruler trims in 1 8" increments.