Chrome Plated 12" Inch Long 20mm Outer Diameter and Approximately 12mm inner Diameter Hollow Shaft 12" Long 20mm Outer Diameter Approximately 12mm Inner Diameter Chrome Plated Shaft 12" inch long 20mm Outer Diameter and Approximately 12mm Inner Diameter(12mm x 20mm x 12")Diameter Hollow Shaft (Chrome plated),this Shaft will make a great CNC, Router or any application needs precision linear movement.