There are two files in he models folder, one is called aura and the other is called aurabind, move them out to use as backups and then put two copies of your new aura in, and rename one of them to aurabind. I had to resize the new aura to 4x the size in Half-Life Model Viewer because it was a 1.1 aura, if your replacement aura was made before 1.2 then you'll probably have to do it as well. You can get HLMV in Half-Life Tool Pack.I tried putting in a custom aura model, but it didn`t work, which files do I have to replace/rename, and are the old 1.1 aura models still compatible with 1.2 ?