Im sorting through things and I have a small bag that has tools, etc for my sewing machine and I found this in it. I dont have the book that came with my machine anymore and I cant figure out what it is used for. The blue part is rubber with grippy things on the bottom. My machine has storage for all the feet but there isnt a slot for this one. Is it some sort of walking foot? I know one of you experts will know what it is! And ill probably go..well, duh..of course thats what it is!!