I recently found this black "Opal" brand brush in an antique store and have it ready for a knot. I think it's needing a 24 mm. knot as a quarter almost fits inside it. If anyone knows that I'm wrong about the size, let me know (I don't have a caliper). What I'm really wanting to get are recommendations for a knot and where to shop for it. I guess I'd prefer a synthetic, something that would look good with a black handle... I'm thinking about a tuxedo knot, but open to suggestions. Any thoughts about the type of knot and good places to shop for it? Thanks!!