Principle with the ball rolling, accompanied by copper, aluminum or resin to maintain the planes, at a certain angle and density of orderly arrangement. Circumference of the lock groove beads using the latest technology, to prevent the ball falling off. ? Product has a low coefficient of friction, axial and radial motion characteristics can rely on rolling friction, gap-free assembly, to ensure that the use of precision. The product is a traditional pillar die sets of replacement products, to high-speed movement, mainly for aircraft and high-precision Die rolling machine tools, machine tool accessories and other fields.