1.our factory produce hexagon screw. 2. size: m6-30x20-250mm. 3. certificate:ISO9001: ... 2000. 4.finish:zinc, black, plain,H.D.G. hexagon screw gradestandardmaterialdiameterlengthsurface3.6(A)DIN(A)Carbon Steelm6-m3010mm-250mm ... insurance by Chinese Property Insurance Company10)Our products are widely used in aerospace, automobiles, motorcycles, agricultural machinery, construction, transportation, ...