Simpson 16d - 3-1/2" Wood Siding Nail, 316 Stainless SteelModel No. T16SND Coating Material. Type 316 Stainless Steel Gauge. 11 Penny size. 16d Length (in.) 3 1 2 Head Diameter (in.) 1 4 Shank Diameter (in.) 0. 12 Shank Type. Annular Ring Shank Head Type. Full Round Head Head Pattern. Checkered Point Type. Diamond Point Approx. Count per Lb. 88 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