Motion Pro is dedicated to producing the most versatile, unique and durable products for professional and home use. Motion Pro tools are designed to be simple to use, yet durable enough to withstand the harshest conditions. One of their goals is to offer tools of convenience. Do it right the first time with Motion Pro Tools. Used for removal and installation of spanner (castle) lock nuts. Premium quality high-carbon steel. Heat treated for strength and durability. Durable hot black oxide finish. Laser-etched with Motion Pro logo and part number. Lifetime limited warranty. Detailed Specifications: Equivalent to Kawasaki tool 57001-1450 and 57001-1597. Large end socket dimensions: 39 mm OD x 30.5 mm ID x 7 mm pin width / 4 pins. Small end socket dimensions: 26 mm OD x 19.9 mm ID x 6.5 mm pin width / 4 pins. 1/2-inch drive.