It definitely isn't a 21mm knot as the other reviewer mentioned, it's around 23-24mm to my measurement and the loft is, indeed, around 55mm. This is probably the best Omega brush to face lather with atm, imo. It doesn't get a perfect score because it isn't the 26mm knot (or more) with a 50-52mm loft that people who face lather are generally looking for in a boar brush. Because it has additional scrub when compared to Semogue hair, I would say the experience is comparable to a shorter Semogue 610 on the skin, even if the 610 has better contact with the tips.