A picture of the "Half Square Ruler". Basically, it takes a bit of time and effort out of the mathmatics of making half square triangle. example:for 3" finished, you need rectangle 3"x 4". Just add an Inch. You still sew two (one dark,one light) fabrics together. It is on a rectangle,[not a square] use the ruler in the way suggested in the little diagram, and SEW on the LINE, and cut between. This is the different bit. Haven't time to show any pictures of it being used yet, got to do the ironing and get ready for Easter Break.If interested I have an email and Aust. phone #