You cannot "open" part 4 individually. You must initiate the extraction from Part 1 .

Older file systems cannot handle individual files larger than 4GB.

As of April 2026, is identified as a specific segment of a multi-part compressed archive, most commonly associated with a 2GB split-archive distribution of Elden Ring . Because large games are often broken into smaller chunks for easier downloading and uploading, this file represents the fourth piece of a larger set. Understanding Multi-Part RAR Files

Software like WinRAR or 7-Zip is required to join these segments back into a single usable folder or ISO. How to Extract "ER_2GB.part04.rar"