Harbour Side Dining Chair, Black Star Base w/Casters

What Audo Copenhagen says about it

Once you’ve chosen the Harbour Chair shell style that will be cradling and supporting your body, you can now also choose a clover-shaped swivel base so you can spin around as needed – and roll around as wanted, should you opt for castor wheels. The base is available with either swivel or swivel with return options in three finishes – polished aluminum or powder-coated aluminum in black or light grey. All Harbour Chairs have been upgraded with extra foam in the seat for better sitting comfort, increasing from 15 mm in thickness to 25 mm.