MATTE BLACK FINISH: Rollator plastic knob has a durable matte black coating. This finish won't wear over time and provides sufficient texture for gripping. ZINC-PLATED STEEL: Bolts and washers for walker accessories are made of zinc-plated steel. They'll withstand moisture and weather conditions when you're out and about. NON-SLIP: Rollator accessories won't slip. This helps to make the walker sturdy and safe to use. EASY TO USE: Driver walker accessories require simple assembly. Attach in just a few minutes. APPLIED WITH: Drive rollator accessories package includes 2 plastic knobs and 2 bolts with washers. These can be easily assembled by hand. When shopping, please pay attention to the size and dimensions of the product to ensure that it meets your needs. In the title and description, we have provided detailed information about the product, including its features and specifications. We want you to be completely satisfied with your purchase, so if you have any questions or concerns, please don't hesitate to . We are here to help and will do our best to assist you. Thank you for choosing our product. We hope you enjoy it!