Prowler Sled Feet Q

Ive just bought a Prowler for my gym. we’re looking to use it on a polished concrete floor, but want to mark it - we also use it on carpet - is there something I can attach to the feet so it will move on both surfaces without scratching the concrete?

Problem solved! Boys at Elite got back to me: http://tinyurl.com/7pa3suf

what did they recommend if you dont mind me asking