A formal dress that is fitted at the top and progressively flares out from the waist, giving a "A" shape, is a sleeveless long A-line side high slit evening gown. The dress lacks sleeves, exposing the shoulders and arms, and frequently has a high slit on the side of the skirt, facilitating movement and revealing a bit of leg. Black-tie galas, proms, and other formal occasions are frequent venues for this kind of gown.