Used on injection molding for tight fastening. No need to counterbore or drill the boss hole as the insert has a guide pilot. All nuts are made of high quality brass, which has high hardness, deformation, and reliable for long time use. Easy to install: As long as the insert has a valve channel, there is no need to counterbore and drill the hole. Can be installed ultrasonically or by heat into a tapered bore, or molded during injection. Color: Gold Material: Brass Package Contents: 600 x M3x5x4 Nuts Only the above package content, other products are not included. Note: Light reflection and different displays may cause the color of the item in a little different from the real thing. The measurement allowed error is +/- 1-3 cm.