These serial products are applicable to the imported roving frame and spinning frame for the spinning of mixed and pure cotton,wool,jute,silk and chemical fibres. These serial upper roller bearings have balls in two rows,suit to the drafting systems which run at high speed and under a heavy pressure,feature a good sealing performance, a long durability,easy maintenance. After adding pressure it is quick in action,runs smoothly with a small friction and a low driving force consumption. The products withstand the tests by the Textile Machinery Quality Superintendence & Inspection Center under the General Textile Association