91九色人妻_国产精片区_精品色无码_AV资源观看

The company adheres to the strategic direction of "taking science and technology as the root and service as the first", has adhered to the spirit of "ingenuity" for more than 20 years, vigorously developed super hard composite material technology, produced six series and dozens of varieties of diamond composite sheet, and basically met the demand of oilfield exploitation market for different structural strata.