An OTA update for pushed for the HTC One A9 android phone. This was made available to the US unlocked phones and weighed in at 65.87 MB. This can be flashed to any and every unlocked HTC One A9 out there. Here is the screenshot of the update.
As said in the screen shot, this update contains important enhancements including android security patches and bug fixes. It is recommended to use a wireless LAN connection for this update but you can also download it over 3G or 4G. This update will not delete any content on your phone.