A piece of equipment you hang off of your boom on one side of the boat in the water to keep you from rolling back and forth.
Sometimes they are two pieces of plastic framed in metal that open and shut like a barn door.
Sometimes they are a group of plastic "Mexican Hats" that are spaced along a long line.
Apparently they now have flopper-stoppers for trees.
Someone must have been concerned about this tree being planted in a rolly sidewalk during Tropical Depression Lowell.
