Wheel Diameter Tread Width Capacity Per Caster Wheel Bearing Modle number Load Height Swivel Radius (mm) (mm) (kg) Swivel Rigid (mm) (mm) 100 51 270 Polyurethane Delrin 4-4T50S-401C 4-4T01R-401C 141 83 Roller 4-4T50S-401E 4-4T01R-401E Double ball 4-4T50S-401G 4-4T01R-401G 350 Moldon Polyurethane(Iron Core) Double ball 4-4T50S-431G 4-4T01R-431G 350 Moldon Polyurethane(Aluminum Core) Double ball 4-4T50S-471G 4-4T01R-471G 125 51 340 Polyurethane Delrin 4-5T50S-401C 4-5T01R-401C 163 98 Roller 4-5T50S-401E 4-5T01R-401E Double ball 4-5T50S-401G 4-5T01R-401G 450 Moldon Polyurethane(Iron Core) Double ball 4-5T50S-431G 4-5T01R-431G 450 Moldon Polyurethane(Aluminum Core) Double ball 4-5T50S-471G 4-5T01R-471G 150 51 410 Polyurethane Delrin 4-6T50S-401C 4-6T01R-401C 189 117 Roller 4-6T50S-401E 4-6T01R-401E Double ball 4-6T50S-401G 4-6T01R-401G 500 Moldon Polyurethane(Iron Core) Double ball 4-6T50S-431G 4-6T01R-431G 500 Moldon Polyurethane(Aluminum Core) Double ball 4-6T50S-471G 4-6T01R-471G 200 51 450 Polyurethane Delrin 4-8T50S-401C 4-8T01R-401C 239 156 Roller 4-8T50S-401E 4-8T01R-401E Double ball 4-8T50S-401G 4-8T01R-401G 540 Moldon Polyurethane(Iron Core) Double ball 4-8T50S-431G 4-8T01R-431G 540 Moldon Polyurethane(Aluminum Core) Double ball 4-8T50S-471G 4-8T01R-471G Full double-layer heat-treated bead disc. Surface galvanizing treatment. Oilable screw. High and low temperature resistant grease. The thickness of base plate is 6mm. The diameter of the mounting hole is 11.2mm. It can be equipped with direction lock, metal tread brake and nylon double brake. Polyurethane is widely used in casters. Many caster manufacturers use this material. It is a thermoplastic polyurethane elastomer with light weight, impact resistance, wear resistance and corrosion resistance. Why choose this material? Because he has some unique characteristics: 1. Good wear resistance, 5-8 times higher than that of nitrile rubber; 2. Good bending strength and elasticity; 3. High tensile strength and fracture elongation 4. Strong tear resistance; 5. Moderate temperature resistance (- 50 ℃ ~ 85 ℃), up to 120 ℃; 6. Good oil resistance, water resistance, mildew resistance and solvent resistance; 7. Good aging resistance; 8. Large adjustable range of hardness (Shore 15A ~ 98a); 9. Low compression set rate. 10. The color can be customized according to needs. Of course, this material also has certain limitations. It can not be used on some special types of casters, but generally, this material can be widely used.