The Strong-Drive SDCF Timber-CF screw is a structural fastener available in a variety of lengths and is designed for cross-laminated timber construction, mass timber construction and general interior applications. These 0.315"- and 0.394"-diameter structural fasteners provide uncompromised strength for these demanding applications. The large flat head with under-head nibs provides for clean countersinking. The yellow zinc, fully-threaded screw, with a proprietary unique point, provides fast starts and excellent withdrawal resistance. For interior and dry applications only.