MATTE BLACK FINISH: Rollator plastic knob has a durable matte black coating. This finish resists wear and provides texture for secure gripping. ZINC-PLATED STEEL: Bolts and washers for walker accessories are constructed from zinc-plated steel, offering resistance to moisture and weather conditions. NON-SLIP: Rollator accessories provide a secure fit to help ensure walker stability and safety. EASY TO USE: Walker accessories require simple assembly. Attach in just a few minutes. INCLUDED: Rollator accessory package includes 2 plastic knobs and 2 bolts with washers. Components can be easily assembled by hand. When shopping, please review the product size and dimensions to ensure compatibility. Detailed product features and specifications are provided in the title and description. For any questions or concerns, feel free to reach out. We aim for your satisfaction and are committed to providing support. Thank you for selecting our product. We hope it meets your needs.