2.5" Hooded dual wheel casters with no collar for hard flooring surfaces such as vinyl, marble or hardwood. Can be used with all Global and Offices to Go chairs. Featuring quick assembly with no tools required - pull existing casters off, and push new casters into chair base. Tested to meet or exceed ANSI / BIFMA standards and is compliant with the emissions guidelines set by the GREENGUARD Environmental Institute. Set of 5. Black with grey urethane treads. Backed by Global's Limited Lifetime Warranty.