1. Materai: Aluminum, Iron, Brass, or other customized requests SUS201,SUS304,SUS316,A2-70,A2-80,A4-80,4.8 6.8 8.8 10.9 12.92. Size: M4-M163. Standard:?DIN GB ISO JIS BA ANSI4. Certification: ISO9001, SGS, CTI, ROHS5.Model: BLFAS-002Q: What is the material of the self-tapping screw?Answer: Self-tapping screws are used for non-metal or soft metal without bottom hole and tapping; self-tapping screws are pointed, so that they can be "self-tapping"; ordinary screws are flat and have the same thickness.How is the surface treatment of the screw handled?1, electroplating;2, hot dip galvanizing;3, machine clear plating. http://www.blfspchina.com/screw...-clasp-sealing-bolt.html