The Klein Tools D507-12 12 in. Adjustable Wrench is made of forged, heat-treated alloy steel for maximum strength and light weight. This tool features extra capacity that allows the use of a smaller size wrench to handle bigger jobs, especially in confined spaces. The precision-machined jaws are individually chosen and assembled by hand to ensure smooth operation. Contoured, plastic-dipped handles make them comfortable to use. This unit features a knurl that turns smoothly for easy operation.