Buttonhole Foot with Slide #3A makes it a cinch to sew buttonholes of the same length.You can then sew as many buttonholes of the exact same length as you want, in next to no time. With Buttonhole Foot with Slide #3A, a sensor on the presser foot determines the buttonhole length and relays the dimensions to the sewing machine.This allows perfectly identical buttonholes to be sewn again, until the size is changed. Buttonhole Foot with Slide #3A is therefore ideal for sewing button plackets on garments and home furnishings.