I wish I knew the proper name for you, but I purchased a small plastic plate and it screws onto the base. I get a perfect 1/4" seam.
Another option is to buy "mole skin", you find it in the foot care section of stores. Find the perfect 1/4" point, and place a piece of the mole skin across the bed. Your fabic would lay right beside it as you stitch. It is raised, so the fabric doesn't jump over the top.
Enjoy that 221, you'll never regret its purchase
