Linear Motion System Chrome Plated 4.58 feet (55 inch long) 20 mm Diameter Shaft With Two slide unit with one pre-installed Bearing Two Aluminium Shaft Support 4.58 Feet (55" long) 20mm Diameter Chrome Plated Shaft With two Aluminium slide unit (has one LB20UU bearing pre-installed) and Two Aluminium Shaft Support, this system would be used for building a low cost cnc router or an XYZ table.