Simpson Collated #9 x 3" T-25 WSV SUBFLOOR Screw, Yellow-Zinc 500-PkModel No.. HCKWSV3S Coating Material. Yellow Zinc Coated Screw Size. #9 Length (in.) 3 Head Diameter (in.) 0. 333 Drive Type. T25 6 Lobe Head Type. Rimmed Flat Head with Nibs Shank Type. 2 3 Threaded Shank Thread Type. Variable Thread Design Point Type. High Low Threaded Point Compatible Tools. Quik Drive PRO300S Packaging Qty. 1000 Simpson Strong Tie has re engineered its popular subfloor screw to reduce driving force and increase installation speed.