Hooks are load-transmitting components that are most often used in conjunction with chains and other equipment. Products such as eye hooks, clevis hooks, grab hooks, shank hooks, swivel hooks, and S hooks can be used to connect lifting and rigging attachments. Most industrial hooks are forged from alloy steel, carbon steel, or stainless steel and then heat treated, quenched, and/or tempered. They are then painted, self-colored, or finished with yellow chromate or bright zinc. Painted hooks come in colors such as red, blue, yellow, brown, and orange. Galvanized hooks are treated with zinc to provide corrosion resistance. They have a silverfish appearance and are designed for outdoor or marine applications. Some hooks are embossed with information such as chain grade, fractional size, and country of origin for traceability purpose. For example, clevis hooks and grab hooks may be rated for Grade 63, Grade 70, or Grade 80 alloy chain. Fractional sizes for hooks are measured in English units such as inches (in) or metric units such as centimeters (cm). Common English sizes for hooks include: 1/4, 3/4, 3/8, 5/8, 5/16, and 1/2 inches. Common metric sizes for hooks vary by manufacturer, distributor, or supplier.