Simpson 8d x 2-1/2" 15° Wire Coil, Full Round Head, Ring-Shank Nail 316 SS 12 Ga.Model No. T12A250PN Coating Material. Type 316 Stainless Steel Gauge. 12 Penny size. 8d Length (in.) 2 1 2 Head Diameter (in.) 1 4 Shank Diameter (in.) 0. 099 Shank Type. Annular Ring Shank Head Type. Full Round Head Head Pattern. Checkered Point Type. Diamond Point These framing nails feature an annular ring shank that increases withdrawal resistance to provide a secure attachment. Key Features Checker pattern on head blends with the wood grain,