It is a security update, version 2.50.617.2. It updates phone’s security with patches from July. Update’s weight is 277 megabytes and, as stated in the title, is available only to the US owners of unlocked HTC 10. If you are a (more or lesS) proud owner of one, make sure to charge your phone and stay in range of WiFi, as downloading 277MB will take a while. Toodles.