NOTE: According to the manufacturer, the M60 mic was discontinued and replaced by the M65 mic, which is made for the AC900, 910, and 920 model headsets.
If you want to save money, don't trust third-rate replacements. Sure, these same replacements may seem like a good idea because they are cheaper, but when they don't fit or don't endure, you lose out and end up paying more.
The Avcomm M60 Electret Replacement Mic (P/N: P4-010) is an OEM replacement that fits with Avcomm headsets AC-900 and AC-747, so you know it is the real deal. It is an amplified electrets microphone that fits most flex-boom models. With its construction and design offering superb quality and performance, you might not need another.