omlib-1.12.2-3.1.4-249.jar is a release file of the Minecraft mod OMLib, made for Minecraft 1.12.2. It was published on January 30, 2020 and is 0.2 MB in size. For the full description, screenshots and every other version, visit the OMLib mod page.
How to install: Put the .jar into the mods folder (.minecraft/mods) and start Minecraft with the matching mod loader profile.
