This is a Blue-tinted skybox for use with the Texture Replacer mod.
Installation instructions:
0. Install Texture Replacer
1. Delete any other skyboxes you have installed.
2. Delete the files in the Texture Replacer/EnvMap folder (If you want the reflections on Kerbals' helmets. Not necessary in newer versions of Texture Replacer).
3. Copy the desired files into your GameData folder.