Hex head fine-thread bolt is hex bolt with smaller thread pitch than standard coarse thread. Fine thread features larger core diameter, better anti-loosening performance and higher connection precision. Common strength classes:8.8,10.9,12.9. Material: carbon steel or alloy steel; finishes: blue-white zinc plated, color zinc plated, Dacromet, black oxide. Widely used for precision machinery, vibration equipment and hydraulic assembly.