It uses Mesh, but it doesn't use CharacterMesh.
The body parts of a character are meshes. Each mesh has a MeshID which tells it what kind of shape it should be. All you need to do is get the MeshID of the package's body parts' meshes, and then use a script to check if these MeshIDs are the same as the MeshIDs or the meshes of the body parts that the player you are checking has.
Accept if this helped. Thx