Polyurethane Tyre, RoHS, Nylon Hub, Medium Duty, Series M22. Swivel forks are electro-zinc plated, white RoHS compliant Single bolt hole mounting Quiet and smooth running PA6 hub with cast poly tyre and roller bearing Corrosion, abrasion and shock resistant Double ball race swivel head castor Temperature range -30°C to +80°C Hardness 95+/-3 Shore A Wheel series A