This is a free edition of AllSky!
It contains 10 skies from the AllSky set for use in your environments.
Provided as 6-sided cubemaps sized from x1024 to x2048 per-side along with an equirectangular cubemap texture from 4k to 16k in size.
Each has an example lighting setup scene.
Please rate if you find AllSky Free useful.
The full version has 220+ skies and is available here.