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

This 300-piece inner hexagon bolt set contains a variety of Type 12.9 grade socket head screws made from high carbon steel with a black oxide finish. The set includes cup head (socket cap), cylindrical head, and round head bolts, providing versatile fastener options for different mechanical and industrial uses.

Grade 12.9 screws are among the strongest standard fasteners available, offering exceptional tensile strength and durability, making this kit suitable for high-load applications and precision assemblies in robotics, machinery, structural frames, and more.

All screws are neatly organized in a sturdy plastic compartment box for easy access and classification, saving time during assembly work or repairs.