Hex head cap screws are used to secure an object within or against another object. Yellow zinc plated fasteners have good corrosion resistant qualities and are a good choice for indoor and industrial applications. Class 10.9 fasteners are heat treated and are similar in strength to grade 8 fasteners. They are stronger than class 8.8. They are used by contractors, designers, OEMs, automotive repair and maintenance staff for critical joints and high stress applications. Tensile strength: 1,040 MPa or about 150,000 p.s.i., similar to SAE grade 8. Head marking 10.9. Made from alloy steel.