It's a simple Flashlight 1.7.10 mod (from: https://www.planetminecraft.com/mod/flashlight-mod/) ported in to 1.12.2 and newer versions of Minecraft

It's add only a flashlight and battery.

Flashlight works in mainhand and offhand. It fits perfectly with the HardcoreDarkness mod:

!1

Battery installation:

Take the battery to your offhand and the flashlight in your hand, then right-click

Crafting:

!f

!b

Config:

!c

[ !! ] In my mods 1.12.2 version will be always supported at first, so sorry for long waiting time for updates to new versions [ !! ]

This mod can be used without problems on a public Minecraft server.