A21-10A Blind Bolt / Blind Nut Anvil, Standard Length. This standard length anvil is manufactured with hardened tool steel. This anvil is a component of the Blind Nut ”K” Type Standard Driving Tool assembly for use with a Hi-Shear® BG1750 hydraulic power gun. Anvil heads are designed to seat against the shapes and diameter sizes of the sleeve heads of blind nuts and blind bolts.