The MT-HP021 model number is φ50mm. Speaker: 120 ± 3 dB 32-inch microphone Resistance: 20–20,000 Hz Regularity Answer: Omnidirectional Mic Sensitivity: -35±3db Mic Unit Diameter: φ6.0±5.0mm Interface: USB cable length: 2.20±0.01m plus a φ3.5mm stereo jack Weight: 395±5g; Dimensions: 206*93*226mm