It looks like those triangles are elongated. I just found the "Easy Try-Mate" ruler today in a quilt shop that's selling out.
This is the ruler:
http://www.equilter.com/product/8296...tri-mate-ruler
Here's a video on the tri recs and the tri mate (tri mate is at about the 8 minute mark):
http://www.youtube.com/watch?v=DMpowniwtk8
I was excited to find this ruler as I LOVE that sashing! Thanks so much for posting this.