Android 5.1.1 OTA updates and factory images hit certain Nexus devices
Receiving both the OTA update to Android 5.1.1, and the factory image for the same build today, are the Nexus 4 and Nexus 5 handsets. Both models were manufactured by LG. Also today, the HTC-built Nexus 9 tablet (LTE version) received the Android 5.1.1 OTA update and the 5.1.1 factory image.
And wait, there's more. Both the first and second-generation versions of the Asus produced Nexus 7 tablets (both Wi-Fi and cellular) have had the Android 5.1.1 factory image posted on the Google developers site. The tablets will soon receive Android 5.1.1 directly via an OTA update.
source: Google via AndroidCentral