My Woods BB60 same with the metal skirt. I used it for a season, then took them off and put chains on. However, I mow on some very rough ground, as well as some trails through my woods. I was always catching the metal skirt on something and bending it or tearing it up. Since they are flexible, the chains can go all the way to the ground, providing a bit better protection for thrown objects without always catching on the ground, gouging things up, and making it hard to turn. If I were mowing in a smoother area, it probably would not have made as much of a difference.