Riccar RL634DE is a four-thread overlock sewing machine with a three-thread capability, which makes it suitable for both overlocking and rolled hemming. It features adjustable stitch length, differential feed, and seam width, allowing you to customize stitches for various fabrics and techniques. The machine also includes a free arm for sewing sleeves and cuffs and a built-in light for illuminating the workspace. With its easy threading system, tension dials, and snap-on presser feet, the Riccar RL634DE offers user-friendly operation and versatility for a wide range of sewing projects.