729 filter bags are made of staple fiber. Moreover, it is tubular and adopts satin weaving. After heat setting and other finishing treatment, it could be widely used for dust collection, gas control industries, etc., for example, dedusting of cement plant ball grinding casting machine. Its breaking strength is large, elongation is small, acid and alkali proof is good. It can constantly work under temperature of 130 ℃, above the dew-point temperature for a long time. Around 150 ℃ , it can stand for a while. Its lifetime is 4-6 times of glass fiber. It has high air permeability, high dust collection efficiency to 98.99%, and the dust removal is easy.