Hey, I assume that Razer has used a standard norm for the thread. There are 3 common ones that are actually covered by the included adapter. Should fit in 99% of cases. Otherwise send the arm back if necessary.

As I see it, you have a thread with which the microphone is attached to the foot. There are 2 common thread sizes. I had a thread adapter with my microphone and was able to attach it to the arm without any problems. If you tell me the thread, I can tell you whether it fits without an adapter.