Extruder Feeder Driver Pulley gear 38 teeth For MK7 MK8 Gear 3D Printer Part Wheel Bore 5mm Stainless Steel PulleyTeeth:38 teethMaterial:Stainless Steel.Inner diameter:5mm.Outer diameter:11mm.Length:11mm.Hole diameter:5mm.Usage:For 3D printer part extruder makerbot or 1.75mm/3mm filament