You cannot open a .003 file by itself. To extract the content, you must have all the related parts (e.g., .001 , .002 , and .003 ) in the same location.
Do you have the of this file, or are you seeing an error message when trying to open it? 7z.001 7z.002 7z.003 help please - SourceForge SS-Sav-009_v.7z.003
The software will automatically detect and "stitch" together all subsequent parts, including your .003 file, to recreate the original file. You cannot open a