What is .PACK file extension?
File used by CustoPack Tools, a program used for customizing the Windows theme; contains theme visual styles, sounds, and graphics for Windows icons and the desktop background; can be downloaded from the CustoPack Tools website.
CustoPack Tools themes are distributed as self-installing .EXE files. The PACK file for the theme is contained within the EXE file, so users rarely ever see the actual PACK file. If you would like to access the PACK file, use a program like 7-Zip to open the contents of the EXE file.
You can see a list of software programs here on easyfileopener.org that can open this file type so that you don’t need to search for it on the web. You can then open your file with this extension using a software listed below.