The ledges will be installed and removed by the technical official working on that lane
Use of the ledge is a personal choice - the swimmer can ask the official to remove it if they wish
The ledge is pre-set at water level. The swimmer can adjust the ledge to 2 or 4cm above or below the water by using the dial on the side of the ledge
Coaches, Team Managers and Swimmers are reminded of the FINA laws related to the use of ledges:
When using a backstroke ledge at the start, the toes of both feet must be in contact with the end wall or face of the touchpad. Bending the toes over the top of the touchpad/ ledge is prohibited.
The following video may be of use for those seeking further information: