With this handy trimmer, you can trim 60 degree corners. And so cutting off dog ears before you sew, making sewing easier and more precies.
But you can use the 60 degree corner trimmer also to cut 1, 2 and 3 inch 60 degree triangles (the finished size of the side of the triangle).
The accompanying book contains extensive instructions on the best way to cut fabric with this template. And it also includes the pattern of a Thousand Pyramids quilt you can make with this template.