found in 1969, lhs rock tools co., ltd (hereinafter referred as lhs) is rock tool manufacturer of great antiquity and profession in chinese machinery industry. what make lhs the greatest comprehensive manufacturer in china are 140 thousand square meters, 8 main workshops, more than 600 employees and 300 sets of equipment for heat treatment, machining, inspection, measurement and test. lhs successively imported from europe advanced productive facilities and superior productive techniques in 1986, and passed the iso9001 international quality management system as the first one in the same industry in 1996. high-standard quality management system and strict management control ensure high quality and stability. the quality is at the leading place in domestic market, and even more, some products reach the quality level of world famous brands. the market share and the export volume keep first in the industry in china. lhs main products include tapered drilling tools (drill bits, drill rods, integral drill steels and plughole rods), threaded drilling tools (drill bits, reaming bits...