Fisher WhisperFlo trim represents state-of-the-art solutions for applications that demand ultimate 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