About A Chair AAC 52 office chair by Hee Welling

The design is by HAY. The AAC 52 features the five-legged castor base and adjustable gas lift, paired with the series' signature solid shell. It is also the only product in our About A catalog to offer a front-upholstered variant: a bare shell where only the front face is upholstered.

The shell: recycled polypropylene, what HAY calls "2.0"

The seat and backrest form a single injection-molded shell made from post-consumer plastic waste: this is what the "2.0" in the color names refers to. The material is mass-dyed: a scratch will not reveal a different color underneath, and maintenance is limited to soapy water. On lighter shades, slight variations in hue are inherent to the recycled material.

The base: five legs, castors, and gas lift

The base is a five-legged cast aluminum star base: HAY calls it a cast aluminium five-legged castor base: mounted on castors. Five legs instead of four: this is the standard for stability in wheeled chairs, as a four-legged chair tips over too easily when leaning forward.

A gas lift adjusts the seat height. It is a pneumatic cylinder: a pressurized nitrogen cartridge, operated by the lever under the seat, which lifts the chair effortlessly and locks it at the desired height. It is maintenance-free and can be replaced as a spare part if it eventually loses pressure.

Note on height dimensions. HAY publishes a single overall height for these chairs. Since the seat is height-adjustable via gas lift, this value corresponds to a specific position, not a fixed height.