Both have distinctive blackish plumage over the head, wings and bellies. The Sooty Albatross has a dark back and mantle as well, whereas the Light-mantled has an ashy-grey mantle, back and rump. The two species can also be told apart by the narrow yellow line on the Sooty's bill. Despite the differences between the two species they can be hard to tell apart at sea, especially in poor light. Both species have a white incomplete eye-ring, dark bills and grey feet. They are among the smallest albatrosses, with wingspans of 200 cm (79 in) and are very narrow as well. The Light-mantled, at 2.5–3.7 kg (5.5–8.2 lb) and sometimes to 4.6 kg (10 lb), is larger than the Sooty, at 2.4–2.7 kg (5.3–6.0 lb). Unique amongst the albatrosses they have long stiff wedge shaped tails, the purpose of which is unclear but seems to be related to their ability to dive for food.