Earlier today, Google announced the release of Android 5.1 Lollipop for Nexus devices. The latest version of Android fixes a bunch of bugs that plagued the initial build of Lollipop while also adding support for HD Voice, multiple SIM cards, Device Protection and more.
While Google said that the OTA update will start rolling out from today, it is yet to show up on any of the Nexus devices. Thankfully, Google has also uploaded the Android 5.1 factory images for a few Nexus devices over at its Google Developers website providing users with the option to manually update the device if they want.
As of now, the Android 5.1 factory images are only available for the Nexus 5, Nexus 7 (2012/Wi-Fi) and the Nexus 10, but it should not be long before factory images for other Nexus devices are available as well.
You can download the Android 5.1 factory images from here.