Cat Ba langurs have long, slim bodies with lengthy limbs and an extremely long tail. Their tails can range anywhere from 32 to 35 inches. Cat Ba langurs rely on their tails for balance. Both their hands and feet are black. Underdeveloped thumbs are on their hands. However, their feet have opposable big toes. A brown or black thick fur covers the entire body of the langur. It gives them an appearance like they are wearing a vest. Orange and yellow fur covers the neck and shoulders of this unique primate. Gray yellowish hair sits on their heads and extends on the chin and sides of their faces. Despite this creature being colorful, they have a black circle around their face. Inside includes big, bulging eyes, black ears, and a flat nose. Males and females have the same colored coats. When an infant is born they are a flamboyant orange until about four months of age. It takes several years for a young one to completely change into the colors of an adult. Cat Ba langurs hang out in trees or on the ground, but they prefer steep cliffs. These rocky places help to hide them from human interaction. As well as being amazing climbers, they are also fantastic jumpers. Gigantic leaps are made from rocks to trees and from tree to tree. They complete their longest jumps from high to low areas. In the 1960s, it is estimated their population was between 2,400 and 2,700. Later on in the 2000s, the Cat Ba langur population was reduced to under 135 individuals. Today, there are only 60 left. Slowly, their population is growing again. Poaching was a main threat to the Cat Ba langur population. Hunters wanted parts and bones of the langurs for medicine. Cat Ba langurs are categorized as Critically Endangered. In 2017, the Cat Ba langur was put onto the list of the 25 most imperiled primate species. In November 2000, the Zoologische Gesellschaft für Arten und Populationsschutz (ZGAP) and the Allwetterzoo from Germany created a protection program for the Cat Ba langurs. Cat Ba langurs are not allowed to be hunted or killed anymore, and births of the species have increased.