MekanismExtension-1.2.1 is a release file of the Minecraft mod (Discontinued / Obsoleted) Advancement Plus - Mekanism Extension for Forge, made for Minecraft 1.17, 1.16.5. It was published on March 14, 2021 and is 0 MB in size. For the full description, screenshots and every other version, visit the (Discontinued / Obsoleted) Advancement Plus - Mekanism Extension mod page.
How to install: Put the .jar into the mods folder (.minecraft/mods) and start Minecraft with the matching mod loader profile.