Replace the Polyphonic Harmonizer behind the Muffler in the ATAK® system with this Muffler to attain the "S-Type" sound level (quieter than ATAK®). Built from premium T-304 stainless steel, superior to T-400 series knockoffs (such as 409), to give you the absolute best in performance and durability. Designed to provide maximum flow & power. Precision computer numerical control (CNC) manufacturing ensures an accurate fit.