Check the listing for details. 80Pcs Knurled Insert Nut M4 x 4mm L x 5mm OD Female Thread Brass Embedding Nut. Condition: New. Listed at 12.85 USD. Descriptions:[Material]: These female thread-knurled nuts are made of brass, offering good resistance to rust and oxidation, ensuring a long service life. They are also corrosion-resistant, and acid-resistant.[Feature]: Knurling increases torque resistance and tensile strength, providing a stronger fastening. Precise and clear threading ensures stability and reliability, preventing thread slippage. The embedded nuts include guiding elements, eliminating the need for countersinking, and making the process more convenient and efficient.[Easy to install ]: Knurled nuts are suitable for various plastic heat, including PLA, PETG, ABS, and PP, etc. After the plastic cools and solidifies around the brass sleeve, the threaded sleeve is securely fixed.