Handling multi-part archives like SandCastles.7z.001 from BayFiles requires all associated parts ( .001 , .002 , etc.) to be stored in the same folder before extraction. Using software like 7-Zip, right-click the .001 file and select "Extract Here" to automatically join and unpack the split archive. For more technical details on splitting and joining, see the guide on Binaries4all . How to extract part files 001 using 7zip on windows (2026)