The Quick-Set bobbin of this sewing machine is designed to be easy to use. The six-point feed dogs of the PC-420PRW are designed to allow a variety of materials to be fed into them. The upper thread tension system of this sewing machine makes for consistent quality stitches across all kinds of fabrics. The PC-420PRW has a maximum sewing speed of 850 stitches per minute. This sewing machine differs from the lower cost PC-210PRW model in that it has more computerized stitches (294 in total, including 10 styles of one-step automatic buttonholes and 3 lettering styles, each with 55 alphanumeric characters, as opposed to the PC-210PRW's 50 computerized stitches), the My Custom Stitch feature (which allows you to create your own stitches using the PC-420PRW's LCD screen, and then save them to the machine's memory), and digital stitch length/width control (for more precision). The Brother PC-420PRW comes with a twenty-five year limited warranty.