The external circulation ball nut and end plug ball nut are similar in that they have larger load-bearing capacity and smoother steel ball reflux. The nut steel ball backflow device is made of stainless steel tube, which has higher strength and relatively low operating noise. It has more outstanding performance for large lead and large-diameter ball screws. However, compared to end plug type ball nuts, standard outer loop ball nuts have a larger overall size. The standard nut has a larger outer diameter, and the insertion tube return device can be covered within the circumference of the nut. Our company can reduce the outer diameter size of the nut according to user needs, but the insertion tube return device assembly needs to exceed the circumference of the nut.