Simpson 12d - 3-1/4" Wood Siding Nail, 316 Stainless Steel 25LbModel No. T12SNDB Coating Material. Type 316 Stainless Steel Gauge. 12 Penny size. 12d Length (in.) 3 1 4 Head Diameter (in.) 2 9 Shank Diameter (in.) 0. 113 Shank Type. Annular Ring Shank Head Type. Full Round Head Head Pattern. Checkered Point Type. Diamond Point Approx. Count. 25 Lb (2750) The Wood Siding Nail features an annular ring shank for increased withdrawal resistance and a checker patterned head that blends with wood grain. These nails are