Hand-Drive Screw Strong-Drive® SDWS TIMBER Screw. Designed to provide an easy-to-install, high-strength alternative to through-bolting and traditional lag screws. The SDWS structural wood screws are ideal for the contractor and do-it-yourselfer alike. Common Application: Structural Wood-to-Wood Connections Including Ledgers Features Bold thread design that provides superior holding power Patented 4CUT™ tip that ensures fast starts, reduces installation torque and eliminates the need for pre-drilling in most applications Under-head nibs that offer greater control when seating the head Large washer head provides maximum bearing area (0.75" head dia.) Size identification on all SDWS screw heads Double-barrier coating provides corrosion resistance equivalent to hot-dip galvanization, making it suitable for certain exterior and preservative-treated wood applications, as described in the evaluation report.