Upgraded glass-filled, Nylon, light-duty (RX) is made from a unique high-tech glass-filled nylon (RX). These are superior impact resistance as compared to regular glass-filled Nylon.
The upgraded glass-filled light duty is superior to steel or cast iron in terms of floor preservation and does not absorb moisture like phenolic. Most chemicals, solvents, gases, acids, and steam cleaning are resistant to it. The wheel core is made of glass-filled Nylon.