The QS Add-On: Android 7 is an add-on to the TeamViewer QuickSupport app and is available only for Android 9.0 devices. It is not a standalone app and cannot be downloaded separately. This add-on is designed to enhance the features of the TeamViewer QuickSupport app, which is a remote support app for mobile devices.

With this add-on, users can access advanced features such as remote control, file transfer, and chat support. The add-on is free to use and is compatible with the TeamViewer QuickSupport app.

Overall, the QS Add-On: Android 7 is a useful tool for those who require remote support on their mobile devices. However, it is important to note that this is an add-on and not a standalone app, and can only be used in conjunction with the TeamViewer QuickSupport app.