Apple released the macOS Sierra 10.12 beta 8 for developers with build number 16A313a, along with beta 7 for public testers. This update just come right after a week of last macOS Sierra 10.12 beta release. Both macOS Sierra 10.12 beta version can be download through software update system, which can be found in Mac App store.
As expected macOS Sierra 10.12 beta 8 released with some bug fixes and performance improvements. The final release will bring better iCloud integration as well support for Apple Pay to the web. Siri also included.
This build is being provided to you for testing and development purposes. Should you encounter any problems, please submit a bug report using the online Bug Reporter at bugreporter.apple.com. Please make sure to include “10.12 (16A304a)” in the bug title and description. This information will ensure that your bug is processed quickly.
macOS 10.12 compatibility : You might want to know macOS Sierra 10.12 beta compatibility with different Mac machines. The latest 10.12 macOS can be installed on any Late 2009 or Newest MacBook or iMac and any 2010 or newer models of MacBook Air, MacBook Pro, Mac Pro, Mac mini.
You can check this post to see complete list of compatible Macs.
macOS Sierra 10.12 final version: Before releasing final macOS Sierra you will get some beta releases from Apple and you need to wait for final release, Its expected Apple will release the final version of macOS Sierra after few months in this fall when a new iPhone is expected and iPhone 7 will be the first device that running iOS 10 by default. So, stay tuned test beta versions.
Download macOS Sierra 10.12 from here.