[Fabric 20w17a] v4.2.0-unstable is a beta file of the Minecraft mod Roughly Enough Items Fabric/Forge/NeoForge (REI) for Fabric, made for Minecraft 1.16-Snapshot. It was published on April 23, 2020 and is 1.3 MB in size. Pre-release builds can contain bugs — back up your world before installing. For the full description, screenshots and every other version, visit the Roughly Enough Items Fabric/Forge/NeoForge (REI) mod page.
How to install: Put the .jar into the mods folder (.minecraft/mods) and start Minecraft with the matching mod loader profile.