The hl_extreme_skins_and_sounds.zip file you have requested: Skins / Skin Packs / Half-Life 2: Extreme Mod Skin Pack For Regular Half-life 2 - 7.21mb is not available. Perhaps try browsing all files for the game Half-Life 2 and upload any files you want to share or are missing. This is the only information we could locate:
This is a skin pack from the single player mod, Half-life 2: Extreme. These replace your default Combine NPC's and weapons from regular Half-life 2 and it's mods with those from the Half-life 2: Extreme mod. It's even has the sounds from the mod also.See the readme below for credits and installation instructions.