These are great to build a complex cloud structures, fog banks, etc quickly! these will render in any 3D application that has openVDB implemented. Most common applications are Vray, Houdini, and Clarisse
2 sets of clouds
-Round and Flat
-100 high-resolution clouds in each set and low resolution respectively
-Renders of each cloud
UPDATE: you can see all the clouds here before purchasing.
2 Free Clouds here to test drive them