CNS type muffler belongs to a kind of supporting parts to eliminate noise, mainly belongs to the type of export muffler, and the main use model of CNS type muffler is the Roots fan AR-S series fans. The difference between CNS muffler and CKM muffler is that the length, height and weight of CNS muffler are greater than that of CKM muffler of the same model, so CNS muffler has better performance than CKM muffler in the whole. However, the main models of CNS type muffler only include the models between CNS-50 and CNS-500.