Very useful. I purchased mine -a Swiss-made model-- from an EBay source, and got [excellent advice/] on Which MODEL would fit my 20 + year old old old machine. Do inquire carefully if you are retro-fitting an older sewing machine. The styles come in short shank, high shank, and slanted. Note that sometimes it will tend to pull to the right, so the quilter must be vigilant and compensate as you feed your quilt into your machine. The walking foot is also known as a PLAID MATCHER, if you are seaming two pieces of plaid to perfectly match, this is your best friend!