A complete surround kit combining three 4006A Omnidirectional Microphones and two 4011A Cardioid Microphones, carefully factory-matched to achieve full precision. Even though the standard tolerances on the Microphone Series are extremely low, the surround match is even closer. The specially-selected 4006As are matched within ±0.5 dB on both frequency response and sensitivity. The 4011As are matched within ±1 dB. The natural sound, high sensitivity, low noise-floor and extremely linear frequency response from 10 Hz to 20 kHz (±2 dB) of the microphones make the 4006A Omnidirectional Microphones the perfect choice for all AB Stereo, Decca Tree or surround main array recordings.