STX Headset Replacement Dynamic Microphone Red M102 Dynamic Mic comes with an impedance of 150 Ω, specifically for H22-STX and H42-STX STX headsets. This replacement mic varies in many features including dynamic, electret, amplified, high gain, low gain and ensures best performance. Providing the right one for your communication needs is crucial. In case of uncertainty about this or another model application, help can be offered with a simple phone call.