Set of 4 vintage chairs in solid wood and black leatherette 1960

Set of 4 chairs with solid varnished wood structure and seated covered with foam and black leatherette. Light and discreet hooks on the original leatherette. Note that the original leatherette is slightly greyed in places (use friction). Seat foams piled on the back. Slots on the wood of two chairs (see photos). Seating height: 40 cm.