The Strong-Drive SDCFC Timber-CFC screw (CFC — Countersunk, Fully Threaded, Cylinder Head) is a robust structural fastener available in a variety of lengths and designed for mass timber construction and general interior applications. These sturdy 0.390-in. diameter (10 mm) structural fasteners have strength for demanding applications involving large-sized structural members. The compact cylinder head countersinks and is minimally visible. The fully threaded screw is designed for fast starts and superior withdrawal resistance. The yellow-zinc coating designates that the SDCFC screws are designed for interior and dry applications.