The 680HM an electronic box-x and shape tacking sewing machine with a max sewing field of 60mm x 80mm, the extended sewing area allow to tack most sizes of harnesses, straps, seat belts and safety gear. The needle's penetrating force into the material has been increased. This provides an improved responsiveness to heavy-weight materials. The W type has adopted a large shuttle hook, which reduces the frequency of bobbin-thread changing to enable highly efficient sewing work. Presser foot control mechanism always provides uniform thread tightness (when thickness of material has been changed, the height of stepping presser foot is changed accordingly without tools required).