14 x 4 TimberLOK® Heavy Duty Wood Screw (12) . TimberLOK® Heavy Duty Wood Screws are designed with shear values stronger than 3/8 inch lag screws. The sharp point and aggressive thread angle penetrate the densest woods without pre-drilling. A uniquely tapered head countersinks easily into wood for a sharp flush appearance. TimberLOK® screws come with a proprietary three-step Xylan® coating process that protects against corrosion, even in pressure treated wood. TimberLOK® screws are ACQ approved. #14 diameter shank.