1266.7z.001

Often used in the preservation of old software or magazine scans.

Files named with simple four-digit numbers like "1266" are frequently associated with curated collections, such as: 1266.7z.001

This indicates the first part of a multi-volume 7-Zip archive. To open it, you generally need all subsequent parts (e.g., .002 , .003 ) located in the same folder. Often used in the preservation of old software