Features: 1) WFB is similar to WF in appearance 2) WFB is covered by elastic rubber and plastic mixture while WF has two coats 3) The elastic rubber and plastic metal granules mixed as the first coat, and then PVC plastic as the second 4) WFB & WF are recommended for speeds higher than 1.75m/s 5) Soft, flexible, attrition bearable, noise resistant and unvulnerable to be split out 6) WFC is coated by PVC and brings catenarian balance chain into being 7) Since the gap between the links is eradicated and WFC makes no noise and low cost, it overcomes the weakness of plastic compensation chains 8) Recommended for speeds up to 1.75m/s