Neumann SBK 130 A Sound Diffraction Sphere for KM 183, KM 130/131, KM 131D/A, KM 183D/A, BlackNeumann SBK 130 A Sound Diffraction Sphere for KM 183, KM 130 131, KM 131D A, KM 183D A, Black The SBK 130 A sound diffraction sphere slips onto the KM 130, KM 131 (A D) and KM 183 (A D) pressure microphones. While sounds coming from the front half space are emphasized by up to 2. 5 dB between 2 kHz and 10 kHz, sounds arriving from the rear half space are attenuated by 2. 5 dB max in the range above 5 kHz. Inner DIAMETER 22 mm.