This exhaust silencer comes with a muffler and all hardware to mate with a Varian Agilent Triscroll 300 or Triscroll 600 dry scroll vacuum pump. It is made to lower the sound level produced by the gas compression. Exhaust silencers work by breaking up noise pulsation in the exhaust line. This unit contains a silencer and muffler and all the hardware to install. The TriScroll Exhaust Silencer Kit install manual can be downloaded in PDF format below.