I've had many a beautiful old brush in the shop, but this is the first flat paintbrush among them, and it is the most beautiful of it's ilk I've ever seen!  With a great patina to the wood and metal wrap around ferrule, and the natural bristles (definitely animal hair, but I am not 100% if horsehair or other) darkening beautifully toward the ends, my inclination of course would be to immediately hang it on the wall as a perfect and unusual addition to a beautiful brush collection. But I must say I can't look at those extra extra long bristles without thinking how luxurious it would feel to paint with it!  Really lovely.

 Terrific condition. A little rusting to the metal (steel I believe), pretty minor. The bristles are full and tightly bound, and the wood is in excellent shape.