This is the HL2 Vortigaunt converted for use in Half-Life: Source. The model is fully functional. This version of the model does not suffer from the broken neck issue previous versions had. This has been fixed. This release is considered legal due to the shared files system these Source games use. All legal versions of Half-Life: Source mount "shared models.gcf", which includes "vortigaunt_slave.mdl" which is the basis of this model. Copies of HL:S updated to steampipe won't have the textures used by this mod mounted. My best recommendation in this case is to find a custom skin that you like online.