The rope nest design has a built in cup shape at the top of the buoy that allows the anchor shackle to nest below the buoy surface. This recessed area helps shield the shackle from contacting the boat hull while making a convenient nesting place for the pennant line when the boat departs from the mooring. The hard-skin polyethylene shell is UV protected to resist the weathering effects of sunlight and is foam filled to positively displace water. Sandblasted finish. Tube Through-The-Center design with blue reflective striping. Shackle and hardware not included. T3C mooring collar required. Dia. 18" Tube 2-1/2" dia. Buoyancy 100 lbs.