The drill is a short-tailed monkey up to 70 cm (28 in) long, similar in appearance to the mandrill, but lacks the bright blue and red on the face of that species.
It has high sexual dimorphism in weight, with males weighing up to 50 kg (110 lb) and females up to 12.5 kg (28 lb).

The body is overall a dark grey-brown.
Mature males have a pink lower lip and white chin on a dark grey to black face with raised grooves on the nose.
The rump is pink, mauve and blue.
Female drills lack the pink chin.
The drill is a short-tailed monkey up to 70 cm (28 in) long, similar in appearance to the mandrill, but lacks the bright blue and red on the face of that species. It has high sexual dimorphism in weight, with males weighing up to 50 kg (110 lb) and females up to 12.5 kg (28 lb).
The body is overall a dark grey-brown. Mature males have a pink lower lip and white chin on a dark grey to black face with raised grooves on the nose. The rump is pink, mauve and blue. Female drills lack the pink chin.
Drill (animal)