Authentic Knoll Brno chairs?  

Hello,

Would greatly appreciate any insight. Recently purchased two BRNO chairs advertised as authentic Knoll through CraigsList. The two chair heights rest at slightly varying dimensions, and the tubular suspension is gradually more curved on one of the two chairs. Neither chair has the Knoll/Rohe signature stamped into the base, which concerns me, though one has the Knoll branded nylon fabric beneath the seat bottom, while the other retains the paper "Knoll International" label stapled to the underside. Despite these two good signs, I have not entirely ruled out deceit on the seller's part due to the obvious differences in dimensions. All my sources have stated that the Knoll Brno height is that of 31.5", does anyone know if this is an adjustment made in recent years, or has always been a definitive dimension? Neither of mine appear to be exactly 31.5". Many, many thanks. R