Check the listing for details. ESD Chair Caster Wheels Hard Tread 5 Piece Set. Condition: New. Listed at 56.95 USD. Ergo360 ® ESD (Electrostatic Discharging) Chair Wheels are designed to help prevent and dissipate unwanted static electricity that can damage electronic equipment. Reduce risks and create a safer environment around sensitive electronics and utilities with these casters.Details:They are a standard size that will fit many typical office chairs, stools, etc. Stem length is 7/8". Stem diameter is 7/16". Wheel diameter is 2". This chair wheel has hard treads. Please note, other components and proper flooring may be needed to provide a complete ESD solution. View images for more detail.Stem: 7/16" diameter x 7/8" long (B Stem)Pieces Per Set: 5Tread: Hard TreadsWheel Diameter: 2"Style: ESD Twin Chair WheelsColor: BlackPayment & Shipping:Pricing is per complete set of 5 ESD casters. Specify a quantity of 1 for 1 set.. 2 for 2 sets.. etc. We provide FAST & FREE priority shipping. Satisfaction guaranteed, if chair casters do not meet your needs, just return within 30 days for a refund. Please measure before ordering. If there are any questions, please contact us.Thank you!