1. Unique contour design that allows no recess for foreign accumulation.

2.Perfect waterproof and dustproof by excellent sealing mechanism of triple stage.

3. Excellent durability and smooth rolling.

4. Excellent function and long life by thick molding of Rubber Disc.

5. Specially designed changeable rubber disc on damaged each rubber part.

6. It is recycle product with Clean and Environment by seperatable designed between steel and rubber.