Chungking Bristle are bristles from hogs raised in the region of the Chinese city of Chungking and are considered to be the best for Oil painting, having long, deep flags. Theoretically the longer the flags the better the bristle. Used mainly for oil, acrylic and hobby ceramics. The interlocking 'curved' heads allow retention of shape. 

The longer hair of the Long Flat brushes results in a loose brush with less 'snap'. Once these are loaded up with paint you can make expressive, long, sweeping marks without the need to reload. The leverage of the bristle make them really popular for many oil and acrylic artists