The .rar extension indicates that the PCK file has been further compressed or bundled using WinRAR or similar archival software. This is often done to:
: Compressing already dense package files helps with faster distribution and downloads. pck 999.rar
: In enterprise environments, PCK files are used by Microsoft System Center Configuration Manager (SCCM) . They store update packages, system files, and application data needed to update large groups of client computers across a network. pck 999.rar
Do you have a specific that this file is intended for so I can give you more precise instructions? Cyber Risk Leaders: Main Home pck 999.rar
A .pck file is a specialized container format used by specific applications to store a collection of smaller files.