2.5" Replacement Office Chair Caster Wheels with Spokes (Set of 5) - S4655-5 Add some flair to your office chair! Work as a replacements on most standard chair bases Standard 7/16"x7/8" (11mm x 22mm) grip ring mounting stem is universal to most chair bases 2.5" (65mm) Twin hard plastic nylon wheels - Ideal for use on carpet and plastic chair mats Black