I was comparing a couple of old barber handle brushes this week, I noticed the old Rubberset knots perform differently, whether NOS or well broken-in. First, I have (2) Rubberset 200-2(23/57.25) with knots in roughly the same condition. These are extremely dense, with firm backbone. Certifyd 2 w/Hollow handle (Made in USA) with a 23/58 knot. Certifyd 2 w/Solid handle (Made in USA) with a 23/58 knot Hess Master De Luxe 4 (Made in Germany) with a 23/62 knot Dubl Duck 3 (Made in USA) with a 25/64 knot(2 1/2in) Dubl Duck 3 Vulcanized (Made in West Germany) with a 23/66 knot Rubberset 49-3 without a knot, but 25mm ferrule opening. Should be 63.5mm loft Dubl Duck 4 Set In Rubber (Made in USA) with a 26/69.86 Rubberset 49-4 with a 28/63.5 well-used knot Rubberset 400 with a 25/63.25 slightly used knot The Rubberset Barber handles are all more dense than the Certifyd, Hess, and Dubl Duck. Many of the hollow, thin handled brushes like the above referenced DD, Hess, and Hollow-handled Certifyd 2 are made like a few Century brushes I've had and my C-Mon. Has anyone else noticed this?