5-inch× 12.5-inch circular silencer with 2.25-inch free-flowing spiral straight-through core, wrapped in 4-inch Dx3-inch L diagonal line of stainless steel mesh with silencer. Limited lifetime warranty. Because the length difference between the two channels is equal to half of the wavelength of acoustic wave, when two rows of interference occur, the two rows of acoustic waves cancel each other out, which weakens the sound intensity and makes the sound smaller, thus achieving the silencing effect. The resistive muffler mainly uses porous sound absorbing materials to reduce noise.