NVIDIA is pretty good about regular updates for its SHIELD line, and the Tablet twins are the recipients of the latest bumps. Update version 4.3 for the original SHIELD Tablet (the one with the stylus) and 1.4 for the newer SHIELD Tablet K1 are basically identical, and in both cases the biggest addition is an update to Android 6.0 that brings the security patches to July of this year. The rest of the changes are pretty minor bug fixes and other small adjustments:
Conformity with OpenGL ES 3.2
Additional optimizations to Android Doze
Fixed issue with intermittent Auto-Rotation shut downs
Fixed audio playback stutter when the display is off
Update to Android 6.0 Security Patch Level July 1, 2016
Overall stability and security improvement
SHIELD updates tend to go out to everyone at once, so check your Settings menu and you should see it sometime today. Remember that post-Lollipop devices need to be completely stock in order to receive an over-the-air update. And before you SHIELD Tablet LTE owners mention it down there in the comments, yes, NVIDIA says the update is coming to you as soon as the company gets carrier approval. As we all know, it might take a while.