The first wireless headphones where bluetooth and worked on the first Makro Racer.
The second wireless headphones where 2,4Ghz and the worked on the Makro Racer 2 & the Gold Racer Models.
The Third wireless headphones with the white botton on the side will work with Makro Racer 2 & the Gold Racer Models & the Nokta Impact.
Hope this answers your question

and here is the post from another thread that explains it a bit better.
"The 'original' Racer used the first wireless set that were a Bluetooth design I believe and NOT the modern 2.4 Gig. headphones.
The 2.4 Gig. are supposed to work on the Racer 2 and Gold Racer models, and if they are the latest headphone with the little white button on the side, then they will also pair-up with the Nokta Impact. I have my first release sample of the 2.4 Gig and they work with my Racer 2, in which I leave the dongle since I mostly use those headphones with the Racer 2. I am waiting on the modern 2.4 Gig w/button for use with my Impact. Oregon Gregg has a set of the recent 2.4 Gig. headphones w/button for his Racer 2 that I tried on the Impact and they work fine.
But, as Dilek stated before, the newer 2.4 Gig. wireless are not compatible with the original Racer."