1.Dimension: 11mm (height) x 9mm (outer diameter)
2.Effective diameter: 7mm
3.Shaft/Bore size: ø5mm
4.Material:Stainless Steel
5.High Quality Stainless Steel MK8 Drive Gear
  give 35% more power over the MK7 for gripping
  plastic filament in 3D Printers, Deep grooves
   give good hold for both 1.75mm and 3.00mm filament.
6.Fits 5mm Shafts with Allen / Hex grub screw.