Bentwood armchair, design Oswald Haerdtl for Thonet, 1950s

Beautiful bentwood chair, not easy to find design by Oswald Haerdtl for Thonet, 1950s.
More rare than model 515 which has some characteristics in common, but is different, especially where the armrests are concerned. The chair is very comfortable and considering its age in a very good condition, with signs of usage matching its age. One of the armrests has some play, but is solid.