The global MIUI 9 rollout continues with Xiaomi Redmi 3s and Xiaomi Redmi 3s Prime getting the Nightly update. The firmware version is MIUI V184.108.40.206.MALMIEK and is 376 MB in size and is based on Android Marshmallow with an April 2017 security patch.
Bear in mind that this is a Nightly build. Xiaomi pushes Stable update to random users and if feedback is going well, the company will roll it out to everybody else.
MIUI 9 already arrived to plenty of devices - from current flagship Xiaomi Mi 6 to the Redmi 1s from 2014. The new user interface version brings Smart app launcher, image search, split-screen multitasking, reviewed design and plenty of fixes and optimizations.