Large black chair wheels with soft polyurethane treads that do not slip and scuff like hard nylon wheels. Soft treads to help protect hard floor surfaces. Compatible with many typical office chairs, stools, etc. Large wheel diameter of 2.5" for easy rolling on hard and soft surfaces. The top metal stem 7/8" long and 7/16" thick. Pricing is per 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.