... DN:15~65MM Used for fesh air fan. ISO9001: 2000, ISO14001:2004, RoHS and CE ; Fresh air fan coil flexibe hose;DN:15 ... ~65MMUsed for fesh air fan.ISO9001: 2000, ISO14001:2004, ... RoHS and CE ;1)Used for fresh air fan of air-conditioning, Durable, excellent flexibility, Notable vibration absorbing, noise reduction ...