Specifications:Name: Drill Chuck & Hex WrenchMaterial: Carbon SteelSurface: Black finishSpecification: 3， 4， 5， 6， 8， 10， 12 mmLimit ring Role:Mainly for fixing the drill bit， limited the depth of drill holes， make depth of the hole consistent. More convenient to roundwood mortise Of Use.Package included:7x Drill Chuck1x Hex Wrench