I do have one of those but have not used it. Don't know why. When I was working befor and knew Iwas going to retire. I bought a lot of things I thought I would use of like. I guess I need to go ahead and use it. If I remember correctly I believe I got it to help with curves. Sorry I can't tell you how it works or anything about it. I love gadgets. LOL But I have heard it works very well for quarter inch seams and wondeful for curves.
BillsBonBon