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-in. diameter structural fasteners provide uncompromised strength for these demanding applications. The large flat head with underhead 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. Strong-Drive® SDCF TIMBER-CF Screw — 0.315 in. x 5-1/2 in. T40, Yellow Zinc (250-Qty) (Pack of 39).