THX did not mention the physical size of the Onyx, but from the images, it looks smaller than the average pen. It makes use of the USB-C port, addressing the lack of a 3.5mm audio jack on most phones these days. You can even fold it when not in use, as the two ends attach magnetically. This allows it to be used as a cable tie for your extra long headphone cables. And if you want to use it with a PC, there’s also a USB-C to USB-A adapter.
The THX Onyx is available to us in Malaysia, and you can get it via the Razer online store. Probably not too surprising, since the two companies work together quite a lot in the past. It is very pricey though, coming in at RM1190.