: "Checker Packs" are often bundles of tools used for credential stuffing or mass-checking leaked databases against specific websites. These tools are often flagged as "Riskware" or "Malware" because they are frequently "cracked" versions of paid software containing hidden backdoors. RAR File Performance

: Generally better than ZIP but slightly less efficient than 7z for large data sets.

: Fast extraction, though it requires specialized software like WinRAR or open-source alternatives like 7-Zip.

If you are simply looking for a review of the RAR compression format used for such packs: