Platte River 110306, Wood Specialties, Buttons & Plugs, 1/2" Birch Flat Head Plugs, 1000-pack End grain plugs have a tapered shape for a snug fit. Specifications: Height=1/4 in, Hole Diameter=1/2 in, Outside Diameter=1/2 in Specifications: Species=BIRCH, Taper=1 degrees