... produce hexagon screw. 2. size: m6-30x20-250mm. 3. certificate:ISO9001:2000. 4.finish:zinc, black, plain,H.D.G. hexagon screw ... ,45#8)thread;BSW,BSF,UNC,UNF etc.9)certifications: ISO9001:2000, the Seventh of Consumers Trust Product in Hebei Province, the ...