Hex bolt with captive washer is a bolt and washer assembly that protects the seating surface. The captive assembly prevents the washer from falling off. Yellow zinc plated fasteners have good corrosion resistant qualities. Class 8.8 fasteners are heat treated and are similar in strength to grade 5 fasteners. Tensile strength: 800 MPa or about 118,000 p.s.i., similar to SAE grade 5. Head marking 8.8. Made from medium carbon steel.