Apple today seeded the fourth beta of macOS 10.12.4 to developers. This update comes a week after the release of the last build. In this version we find Night Shift. This allows you to change the color temperature of the screen at night which is better on the eyes. Other than that we’re not sure what’s new in this version. Likely some bug fixes and other minor improvements.
To get this version developers can go to the Mac App Store and find it under updates. If you’re not on the beta yet you can go to the Apple Developer Center and download the installer from there.