Set of 4 black plastic and metal chair casters. - Quantity: 4 - Color: Black - Type: Casters - Material: Plastic and metal - Application: For chairs Used on Herman Miller legs. Please refer to image 5. These parts are not genuine. They are old and have rust. Because they are in poor condition, one is included as a bonus. They were working fine until removed, but future use is at your own risk. I am an amateur and not a furniture expert. Thank you for looking.