Klein Tools' 4-Inch Adjustable Wrench (standard capacity) is made of forged, heat-treated alloy steel for maximum strength and light weight. The precision-machined jaws are individually chosen and assembled by hand to ensure smooth operation. Contoured, plastic-dipped handles make them comfortable to use. For more than 160 years, Klein Tools has manufactured premium-quality, professional-grade hand tools that deliver the performance, durability and precision needed to get the job done right. Our family of engineers, workers and craftsman continue to put six generations of expertise into every tool we create by using only the highest quality materials, superior workmanship, and keeping manufacturing as close to home as we can. Klein isn't just the name of our company, it's also our family name. And since we're an American company that's family-owned and family-run, you know you can count on us to be here tomorrow. Klein Tools doesn't just make great products, we make great products that stand up to the demands of the professionals who use them every day ... Since 1857. The Klein D506-15 15-Inch Adjustable Wrench-Standard Capacity, Plastic-Dipped Handles is forged heat-treated alloy steel for maximum strength and light weight. The Klein D506-4 4-Inch Adjustable Wrench-Standard Capacity, Plastic-Dipped Handles has high polish chrome finish. The Klein D506-4 4-Inch Adjustable Wrench-Standard Capacity, Plastic-Dipped Handles has precision-machined jaws that are individually chosen and assembled by hand for smooth operation, is heat-treated for long life, a knurl that turns smoothly for easy operation, contoured handles for comfortable use, is chrome-plated for rust resistance, and the rail is ground for precision fit.