These threaded insert nuts are widely used in 3D Printing, molding, for fastening, can be installed in the cone hole by ultrasonic or heat,or in the process. Since the insert has a conduction valve, there is no need to back-drill and counter-sink the hole. Type:Metal Lock Nuts Specification:B:80PCS M3x5x4=10Pcs M4x4x6=10Pcs M5x5x7=10pcs M5x6x7=10Pcs M5x8x7=10Pcs M5x10x7=10Pcs M6x6x8=5Pcs M6x8x8=5pcs M6x10x8=5Pcs M6x12x8=5pcs Color: Gold Material: Iron Package Contents: 1Set x Heat Insert Nut Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in the picture a little different from the real thing. The measurement allowed error is +/- 1-3cm.