These GB28 standard hexagon head reamed hole bolts are made of high-quality high-strength steel, heat-treated to **Grade 8.8** for excellent tensile strength, shear resistance and fatigue stability, suitable for heavy-duty mechanical connection and precise positioning. Featuring a precision reamed shank and reamed tail design, they have tight dimensional tolerance and can closely fit with reamed holes, effectively bearing transverse shear force and preventing radial movement of parts under load and vibration. Equipped with a standard hexagon head for easy wrench installation, the threaded section provides stable and reliable locking force. They are widely used in construction machinery, equipment assembly, mold fixing, transmission structures and other working conditions requiring shear resistance and high-precision fitting. Each bolt is strictly inspected for hardness, straightness and thread accuracy. Available in full sizes with factory direct supply, providing professional high-strength reamed hole fastening solutions for mechanical engineering users.