Lamprey Hardware #14 Winter Plug Expanding for 3.25-3.5 inch openings. This will fit 3" PVC fittings and couplings but will not fit 3" sch40 PVC. When untightened the top part is 3.40 inches in diameter. When Lamprey plugs are tightened fully 55% greater tightness than conventional plugs. Used for a variety of uses like closing your swimming pool or spa, motors, bathroom sinks or showers, and more. Guaranteed a tight fit. Lamprey Hardware item # LHP14