Pair of vintage 1960 Plia chairs by Giancarlo Piretti for Castelli

Pair of old folding chairs in smoked perspex and white lacquered metal model Plia design Giancarlo Piretti published by the Italian firm Anonima Castelli circa 1960 in good condition. They are very clean although one has slight paint loss on the bottom. They are complete, all the original skates are present. The particularity of this chair is its clever aluminum ball joint connecting the seat, the backrest and the legs, and allowing the chair to occupy a very small space (only 5cm) when folded. The seat is solid. We find the original label under one of the two with Plia Italy written. One chair measures 75cm in height, 43cm for the seat, 47cm in width and 50cm in depth.