A01 Twin Wheel Design Caster E23 Design Caster E23 Institional Caster E16 Stainless steel Institional Caster A10 Light Duty A11/A12/A13 Shopping Cart Caster/Walkway Caster A21 Medium Duty A22 Stainless Steel Medium Duty A23 Medium Duty A31Medium Heavy Duty A32 Medium Heavy Duty (For Tool Box) A33 Medium Heavy A34 Medium Heavy Duty A41/A42 Heavy Duty/Kingpinless Heavy Duty E41 Heavy Duty(European Standard) E51 Super Heavy Duty(European Standard) E33 Scaffold Casters A61 Kingpinless Heavy Duty A71 Kingpinless Extra Heavy Duty