Redux Textures is an interface texture replacement pack, containing AI upscaled interface textures for WoW Classic / Wrath of the Lich King.
Where possible, textures from newer game versions were used, such as for the login screen buttons and so forth. Anything else was upscaled using AI upscaling.
The texture pack does not need any addons to run, and should have virtually no impact on game performance. That said, included is a very simple addon that will handle texture replacement for Leatrix Plus, Leatrix Maps and Auctionator - if not used, these addons will use their own custom textures that were based on non-upscaled vanilla textures and will look dated and low resolution.