Simpson Strong Tie C211ARN1 Smooth Head Full Round Head Annular-Ring Shank,1-Inch,11 Gauge,Copper,229-Piece 3/8-inch head diameter and .120-inch shank diameter Large flat head provides extra bearing surface Annular ring shank increases pull-out resistance Longer lengths ideal for installing curved Spanish roof tiles and thicker slate Aluminum nails also available with a screw shank