It is made of various fabrics, supported by steel ring and high frequency heat sealing technology. Outer diameter is fixed. It can work normally between high temperature 110℃ and low temperature -40℃. It can effectively prevent dust, water, oil, emulsion and chemicals. It has neat appearance and it not easy to deform. Based on its tightness and firmness, it can be used for ventilation and dust removal of many machines. The required diameter and length can be determined according to the specific requirements of users.