Chair wheels designed with a soft polyurethane tread to help protect hard floor surfaces. They are a standard size that will fit many typical office chairs, stools, etc. Metal stem length is 7/8". Metal stem width is 7/16". Wheel diameter is 2". Upper black nylon barrel diameter is .625", this "neck" is a visually aesthetic feature that is usually selected to best match the existing chair base. Pricing is for a complete set of 5. Specify a quantity of 1 for 1 set.. 2 for 2 sets.. etc. Satisfaction guaranteed, if product does not meet your needs, just return within 30 days for a refund. Shipping is not refundable. If you have any questions, just call toll free.