The Light Tray, also known as Downlight Tray or Downlight Flashing is available only in Gable structures and can be found in the Gable Options tab
When this box is ticked, a downlight flashing will be added to the System Material List in the same colour chosen for the beams.
If there is a reason to change the colour of the Downlight flashing, you can do this by amending the System BOM and creating a Customised Component List