I just purchased one to fit my Brother machine. It looks simular to the first photo here, the bar one. It fits to the machine and you slid the pin to the size you want. Mine uses a locking pin to hold the fabric to center. You then start your stitching and the machine pulls the fabric around. I do have to make sure the fabric doesn't get caught up against the machine as it's moving. But it works great! I can see it being used for lots of things.