Hi Barbara,
Odd you should ask that question. I found a set of these in my sewing room yesterday that I had forgotten all about. I didn't take any of Claudia's classes so I haven't seen what she was using. The clamps that I have are four inches long and are Quick Fix Quilt Clamps according to the label in the package and are to fit a three inch bar. Unfortunately there is no store name, website or contact information on the label. I am pretty certain that I purchased them from a vendor at MQX West last year. I thought that it might be The Calico Kitten but there is nothing shown on their website, so other that now having a name this probably isn't of much use to you! If I remember where I got them I will post the name.