It is a wool breed. There is a wide variation in the percent white to black within the breed. Breed specific markings occur on the muzzle, around the eyes, the ears, the nape of the neck often reaching onto the shoulders, the knees, the hocks, the pasterns and the scrotum or udder.
Random spots occur on the rest of the body.
Not all markings are on every sheep, but enough need to be present for clear identification. The Jacob is a primitive breed. The conformation is similar to a dairy goat. The Jacob is a small sheep with ewes weighing 80 to 120 pounds and rams from 100 to 180 pounds. The body type is lean and agile with fine boned legs set squarely.