12Pcs Leveling 8mm Extruder Springs For 3D PrinterSpecifications:Diameter(OD): 4.8mm/0.19inchLength: 8mm/0.32inchInternal diameter: 3.20mm/0.13inchMaterial: stainless steelGood formability, homogeneous elastic.High plasticity, fatigue resistance, heat corrosion resistance.Environmental protection non-toxic pollution-free.Package included:12 x 3D Printer Extruder springs