As a heavy duty lockstitch sewing machine, GB4-1 model is used to sew canvas, container bags, belts, leather, tent, luggage, etc ... machine. As a heavy duty lockstitch sewing machine, GB4-1 model is used to sew canvas, container bags, belts, leather, tent, luggage ... will not displace under any needle pitch, sticky material or super long products so as to obtain orderly products with beautiful stitches ...