Skyboxes is used in games for sky textures.
This product - zip file- consists of;
1 skyboxes unitypackage
and in addition
1 unity3d skybox material
6 images skybox have got (each other 2048*2048 .jpg files )
1 sphere image for use to 3dsmax , maya or other 3d programs (2896*1448 .jpg file)
unity3d 3 and above