Special Functions: Horn:Special treatment for the plate and thread stem the wheels core use raw ABS material,those make more capable for cauterization-resistant. Wheels:They were made of the polyurethane which are more capable for high elasticity and insulation,with their special corn made by ABS.all of those ensure them for cauterization-resistant and aging-resistant. Appearance:A news vision of warm and clean will bring to you for their white ABS corn and grey polyurethane tire. Application range:The hardness of the tire is 90Aand suitable temperature is -20-80,this series is recommended to use in the smooth environments indoor,especially use in the super grade medical equiments.