These copper nut feature excellent thermal conductivity for quick heat fusions bonding, ideal for industrial applications requiring high strength fastening without deformation under high temperatures. The 420pcs set includes M3M4M5 sizes to accommodate various project needs, eliminating separate purchases for different nut sizes, perfect for DIYers and professional. Make of durability copper, these nut resist rust and exposure, ensuring longevity in humid or harsh environments like lab equipment and outdoor maintenance. Designed for easy insertion without additional tools, saving time during assembly or repairs, making it ideal for quick part replacements in maintenance work. Copper construction, providing safe usage for healths households, especially in 's toy or furniture assembly.