Fisher WhisperFlo trim represents state-of-the-art solutions for applications that demand noise attenuation. Control valves with WhisperFlo trim provide additional attenuation for aerodynamic noise in very demanding vapor or gas applications with high pressure drops. A WhisperFlo cage with an appropriately sized valve body is designed to reduce the noise level up to -40 dBA. For special applications, -50 dBA attenuation can be achieved