Tier2.Release.3.4.1 is a release file of the Minecraft mod Tier 2 for Forge, made for Minecraft 1.15.2. It was published on June 22, 2021 and is 18.9 MB in size. For the full description, screenshots and every other version, visit the Tier 2 mod page.
How to install: Put the .jar into the mods folder (.minecraft/mods) and start Minecraft with the matching mod loader profile.