The Daytona angle round head is made of T-304 stainless steel, TIG welded, with limited service life. The frequency category of the muffler refers to the frequency or frequency category with significant noise elimination. Generally speaking, the frequency characteristics of muffler are octave and 1 / 3 octave. In this regard, there is no unified quantitative evaluation index. Generally speaking, the wider the effective frequency band of silencing is required, the better, the human sensitive frequency category should have sufficient silencing amount, and the frequency band with large radiated noise at the sound source should have large silencing amount, so the effect of noise reduction by using muffler is better.