When deflated, this module has a 3.75m factory form and can hold no crew. Expanded, this module is 10m and can provide living and working space for a crew of 20. Additionally, the unit can be set to rotate independent of its parent ship, providing a comfortable 1g for it's occupants.
For all info please go to my forum thread for this mod:
http://forum.kerbalspaceprogram.com/threads/85364-3-75m-Inflatable-Centrifuge