300pcs/box sType 12.9 inner hexagon screw high carbon steel cup head cylindrical head round head bolt combination set

This 300-piece high-strength fastener kit contains a wide range of socket head bolts in three head styles: cup head (socket cap), cylindrical head, and round head, all made from Grade 12.9 high carbon steel. These bolts are designed for high-load and high-stress environments, making them ideal for use in mechanical assemblies, robotics, structural frameworks, and equipment repairs.

The inner hexagon (Allen drive) ensures reliable torque transmission and ease of installation in tight or recessed spaces. A black oxide finish enhances corrosion resistance and provides a clean, professional appearance.

Each piece is sorted and labeled in a durable plastic organizer box for fast access and efficient storage.