If you have a similar arm, that has the end too thin for Razer Seiren mini, you probably got the reduction in the box with the arm.

Unfortunately, that reduction isnt exactly the same thread size and it chews away the plastic thread from the microphone and eventually makes it too loose.

That's why I made this custom one, that works perfectly, the microphone is staying there nicely and nothing is loose.

CAUTION: As it is still a plastic thread, don't overtighten it! Just make sure it is not loosely flapping around but dont tighten the microphone to it too much or you'll destroy the thread on the print.