Router Conversion Sleeve Tool Bit, made of high carbon steel, reliable and not easy to wear.Product specifications:Product name: Pastlla ChuckColor: BlackMaterial: Carbon steelSize: Inner Diameter: 1/4"(6.35 mm); Outside Diameter: 1/2"(12.7mm)Please see the picture for detailed size.Package contains:4 x Router Conversion Sleeve Tool BitsDue to manual measurement, please allow 1-2mm error. Please allow 5% color error due to different monitors.