Chatmix is available on the Arctis 7+ through our Sonar app, available in SteelSeries GG. Along with Chatmix, Sonar gives you access to more great audio features, such as Parametric EQ, virtual Surround Sound, and Microphone effects. For more information on Sonar, please go to https://steelseries.com/gg/sonar
Need help setting up Sonar's Chatmix features? Please check out this article: How do I Setup Sonar Chatmix?