The Klein 65821 5-Inch extension is designed with a 1/2-Inch socket size. This extension is very desirable for hard to reach areas. Since 1857, Klein Tools has manufactured the world"s finest hand tools. Today, Klein Tools is the No.1 choice among professional tradesmen. We manufacture more than 3,000 tools and accessories, including pliers, cable and bolt cutters, wire strippers, voice-data-video tools and testers, fish tapes, conduit benders, drill bits, insulated tools, gloves and many other high-quality products. Klein Tools" dedication to quality and innovation continues with products available for professional tradesmen worldwide.