"X1.7z" typically refers to a that uses specific configuration settings or command-line parameters. In the context of 7-Zip optimization, "x1" often represents the lowest compression level (Fastest), which uses a 1 MB dictionary size to prioritize speed over file size reduction. Understanding the .7z Format
It can handle archives up to 16,000,000,000 GB. 000 GB. Ultra compression
Ultra compression; can use up to a 256 MB window size but requires significantly more RAM and time. How to Use X1.7z Files 000 GB. Ultra compression