Specification: Color: black Material: plastic, 304 stainless steel, PE material Product Size: rollator knob: 2.4x2.4x2.2cm/0.94x0.94x0.86in, screw: 4.9cm/1.93in, washer: 1.9cm/0.75in Package details: 4 x rollator walker replacement knobs 4 x washers 4 x screws Note: Due to manual measurement, the size and weight may have a certain error. Due to the difference between different monitors, there may be a slight color difference existed.