The Simpson Strong-Drive SDHR Combo-Head screw is a structural fastener designed for cross-laminated timber construction, mass timber construction and general interior applications. These partially-threaded structural fasteners are designed to pull structural members together while providing excellent connection strength. The unique “combination” head allows for effortless driving using either a hex driver bit or T-40 6-lobe driver bit. The SDHR Combo-Head has an interior-grade, blue-zinc coating, a robust knurled shaft and Type-17 point for fast starts and low-torque driving.