A built-in flange protects surfaces from splitting and pull-through by spreading pressure over a large area. These screws are often used to secure wooden posts and beams because their coarse threads dig in. The hex head's six contact points keep sockets in place to avoid slipping and stripping the drive. To tighten, use a wrench or six-point hex socket. Also known as lag bolts.

Drill a pilot hole slightly smaller than the screw to prevent splitting. Head height includes the flange. Length is measured from under the flange.