Each style has 2 tread material PJP: Thermoplastic rubber UAP: Polyurethane (PU) housing and wheel made of high grade synthetic materials, all fittings yellow passivated, wheel made of Polyamide, tread made of Polyurethane, threadguards and precision ball bearing. Available for electrically conductive and watertightness casters. For hospital bed, hospital equipment, catering equipment or other applications.