There is usually a whorl on the crown, fairly forward near the forehead. The dorsal stripe is present but not well defined. Overall body coloration is a grey-black to chestnut brown with the underside to the chin being white. White hair on the side of the head, just under the red cap, extends around the neck like a collar to a white patch on the back of the head. The dark chestnut brown tail is white tipped.
Juveniles are darker in color.
There is great color variation amongst sub-species and individuals. Males can weigh up to about 42 pounds. Females usually weigh 15 to 25 pounds. This phenomenon happens only with some Old World monkeys. The gestation period is 5.5 months.