Upholstered Rolling Tulip Chair?- chair question  

I recently purchased this chair. I believe it is a tulip chair. However, I can't seem to find any examples of identical chairs on the web. Is this a rare version of the knoll tulip chair? Any ideas or insight would be welcomed.
Let me describe it. The chair is upholstered and has a removable seat pad that is attached with velcro. the base is a swivel base that also rolls. It seems to be painted white metal. The seat portion of the chair is dense plastic or fiberglass, also white. Underneath the seat pad there is a "knoll international" sticker affixed to the metal plate. The seat cushion has a tag stapled to it that reads, in part " art metal-knoll corp. Knoll associates division"
Thanks so much!
http://picasaweb.google.com/carrie.rockett/Chair?authuser=0&authkey=Gv1sRgCO2N7LnFv_-x0gE&feat=directlink