This set comes in 2 pieces that support the umbrella or parasol but we do recommend using 4 pieces for full support. This is an essential purchase when buying a parasol to get ultimate use and to enjoy the summer months. To weigh a parasol evenly 2 sets are required (4 segments). As with any product when rubbing against a rough surface material may transfer. If your patio or decking is light in colour we recommend using a liner between the umbrella base and the ground.