Amazon.com: SPAX 4581820800905 5/16” x 3-1/2" T-Star Washer Head HCR (High Corrosion Resistant) PowerLag Contractor Pax (50 Pieces per Box) : Industrial & Scientific
Simpson Strong-Tie 0.220 in. x 4 in. T40 6-Lobe, Washer Head, Strong-Drive SDWS Timber Screw, Exterior Grade (50-Pack) SDWS22400DB-R50 - The Home Depot