All SX4 booms include a integrated shim for RDM masts for secure fit on both RDM and SDM masts.
The outline and width of the tail are crucial for the rig to deliver the right balance between power and control. The outline on the 140 and 160 booms are designed specifically bump n'jump sailing where you want to be closer to the rig for control. The 180 booms has a wider outline to get momentum on the rig to go really fast. A wider tail generates more power and a more narrow tail piece more control. This position varies with the wind strength and windsurfing discipline, therefor each boom size have been developed individually.