I love my ruler foot and rulers. I do all my FMQ on my Bernina 440 and wanted to able to use a ruler to do sashing and outline stitch straight blocks and then go back to FMQ designs. I don’t know what machine you have but I also find my ruler foot easier to FMQ with. No need to change tension from regular sewing and the ability to dial the foot down until just above the sandwich gives my great thread tension stitching.