High Mountain White Badger from Sterling Soap. I have this brush, and it is soft with backbone.
High Mountain White Badger Shave Brush - 24mm x 53mm (Black) - https://www.stirlingsoap.com/collections/shave-brushes/products/high-mountain-white-badger-shave-brush-24mm-x-53mm-black
High Mountain White Badger Shave Brush - 24mm x 53mm (Black) - https://www.stirlingsoap.com/collections/shave-brushes/products/high-mountain-white-badger-shave-brush-24mm-x-53mm-black