1. The filaments on antique brush won't fall off during brushing.

2. The filaments are fixed to the base with high strength stainless steel wire prevented from corrosion.

3. The filaments on abrasive brush should be bended wave shape.

4. The silicon carbide grits inside the filaments won't break off because of the wave shape filaments.

5. The appropriate height and density of the stone polishing brush.

6. The filaments should have the good wave resilience.

7. The filaments should have the long lifespan.