I have 2 seam gauges--one is red and the other is yellow. I purchased the yellow one from Nancy's Notions
http://www.nancysnotions.com/product...+seam+guide.do this was recommended by one of the Craftsy class teachers. The red one comes with a strip to put on the machine--it is called Quilter's Gauge by Dritz. I do not remember where I ordered this from.