No matter what's written there, this headset is NOT Sennheiser -it's EPOS brand. You can read how came to that elsewhere, but in short: Sennheiser sold gaming headset department to EPOS and at first EPOS even used Sennheiser logo on it's products (as eye catcher). Anyway, EPOS has nothing in common with Sennheiser. As far I could findout, EPOS is just a brand sourcing from China.
I bough EPOS GSP 370 about 18 months ago, by thinking it's actually Sennheiser (my headset still has Sennheiser logo, but is made in China) and all I can say is, poor quality for the money. After a year, ear pads started to fall apart, as foam is protruding out at seam -if you google for that, you'll see that's well known issue for EPOS headsets.