A .rar file is a compressed archive. It likely contains high-quality audio recordings (such as FLAC or MP3) or video clips of the 4th session or a 4th part of a specific set.
Files ending in .rar from unknown online sources can occasionally contain malware. Always scan with updated antivirus software before extracting. Blue Jay Jazz Jam BJ_All_Star_Jam_Session____04.rar
The naming convention "BJ" often refers to the Blue Jay Listening Room in Jacksonville Beach, which is known for hosting weekly all-star jazz sessions featuring high-caliber musicians. BJ_All_Star_Jam_Session____04.rar