The file is a community-created animation modification, most commonly associated with the Left 4 Dead 2 (L4D2) modding scene. It typically features custom character movements or physics-based adjustments created by the user RED_LJ . Understanding the "RED_LJ" Animation Pack
For those downloading these files from external modding sites rather than the Steam Workshop: RED_LJ_Animations.zip
: A signature of many RED_LJ collections on the Steam Workshop is the implementation of physics for character hair, clothing, or anatomy. The file is a community-created animation modification, most