After the initial April 2016 Security updates, there is a new build that’s being seeded to some Nexus devices. The new build is MOB30D and is labeled as the regular security and performance update, and is sized around 12 Megabytes for Nexus 5 in OTA (over the air) update. Some other nexus devices did get this build along side the regular security updates for April 16. Since the initial monthly update cycle adopted by Google various OEM’s have followed in these footsteps, and it has increased the overall stability of Android.
With Lollipop 5.0 the system UI has been similar in the more latest versions, minimizing cosmetic changes. The new build over MMB29X is available for Nexus 5, Nexus 6, Nexus 7 (2013) Mobile and Nexus 9 Mobile. The devices got the MMB29X as the April Security update but now seems to have received the second update. The Android version stays at Marshmallow 6.0.1 and hence to major changes are observed. You can also grab the images for you nexus devices at our Firmware section or directly from Google’s developers portal. To check for the OTA update manually go to Settings > About Device > Software updates.