Two-way Radio Adapter

I am looking for a two-way radio adapter. I have a Midland Helmet Headset and a Rino 530HCx 2-Way Radio/GPS. The Midland headset has a dual pin connector on it and teh 530HCx has a single 2.5mm plug. I know there is a China-made adapter, but I don’t know if it will work (see Does anyone know of a US supplier for this?

I was planning to build my own bit if something exist and is not too expensive?

where are you located from?