Hejian Xinlong Drilling Accessories Factory specializes in the designing, manufacturing ,marketing and serving the high performance diamond bits, tricone bits and drilling tools which used in petroleum industry. our bits which size ranging from 2 7/8" to 17 1/2".All the products are made in accordance whit the API spec 7-1,meanwhile our quality ensure system awad the ISO9001 certificate. Furthermore ,the experienced and knowledgeable service team will ensure the superior performance of our products in both the domestic and international markets.