: The versioning indicates this is a stable, iterative update. The "a" suffix often denotes a "hotfix" or a minor revision to version 5.8.4.

What is the of the device you are using this for?

: Enhancing CPU/GPU speeds and battery life.

: ROMs and Kernels are not universal. Installing a file meant for one phone model on another can "hard brick" (permanently break) your device.