Lead Screw - 8mm diameter, 4 start. Standard lead screw round on Z-axis of many printers. Can be used as replacements on Wanhao Duplicator printers. 8mm lead provides fast movement at the expense of torque. Ensure your stepper motor has enough torque to avoid stalling or skipped steps. 

Thread Distance: 2mm Pitch

Distance per revolution: 4 Start x 2mm = 8mm Lead

Diameter: 8mm

Length: 500mm

Can be Cut to Length with Hacksaw or Friction saw, like Angle Grinder or Dremel