... -3400 2.Used in mining,cement,steel,harbor,etc 3.Certificate:CE,ISO,BV,SGS Conveyor roller dia 60-219,length 190 ... 50mm-219mm, length 190-3400mm, which are used in the steel industry, harbor, coal industry, power industry, cement industry, etc2.Tube ... manufacture the rollers and idlers according to the buyers' requirements conveyor belt for coal mining industry