Lag Screw, 3/8 in, 3-1/2 in, Steel, Zinc Plated Hex Hex Drive, 10 PK, Midwest Fastener, Mfr#: 35026

A lag screw is similar to a wood screw, but generally is much larger with a hexagonal head. Lag bolts are designed for securely fastening heavy timbers to one another, or to fasten wood to masonry or concrete.