Offered in wheel diameters from 100-200 mm, metric synthetic casters have swivel brackets made of glass-fiber reinforced synthetic plastic, with double-sealed grooved ball bearings in swivel head, and combination 2-stage directional and wheel brake locks. Wheels have nonmarking thermoplastic rubber treads, and centers of gray polypropylene with ball bearings and thread guard. Standard mountings include threaded stem, expander fitting, and plate styles.