Hackers Help: Need carpet castors for Malkolm office chair

Photo: IKEA.com

I recently bought 2 Malkolm office chairs.  The castors that come with it are not for carpet.  The box said I could get “Punkt” carpet castors, but now IKEA says they are no longer available.  Has anyone found a substitute?  My sweet husband made hardwood floor mats that work well, but I’d still like the carpet castors.  Thank you in advance.

Signed, MissingIKEA