Features: Strong and serviceable: All walker parts and accessories are made of reliable materials, sturdy and suitable for daily replacement. Practical accessories: The plastic star knobs kit can be a good replacement for the corresponding parts of your walker arm that are broken, extending the life of the walker. Specifications: Material: plastic, metal Color: black, silver Size of T-bolt: 5.25 cm/ 2.07 inch Package includes: 2 x Star knobs 2 x T-bolts 2 x Metal washers Notes: Manual measurement, please allow slight errors on size. The color may exist slight difference due to different screen displays.