Hexagon socket head screws, also known as hexagon socket bolts, cup head screws, and hexagon socket screws, may be called different names, but they all represent the same thing. Commonly used hexagon socket head screws come in grades 4.8, 8.8, 10.9, and 12.9. They are also called hexagon socket screws or hexagon socket bolts. They have a hexagon socket head and a cylindrical head. They are categorized by material into stainless steel and iron. Stainless steel includes SUS202 stainless steel hexagon socket head screws, which are common stainless steel materials. There are also SUS304 stainless steel hexagon socket head screws and SUS316 stainless steel hexagon socket head screws. Iron is categorized by strength grade, including grade 4.8, grade 8.8, grade 10.9, and grade 12.9. Grade 8.8-12.9 hexagon socket head screws are called high-strength and high-grade hexagon socket bolts.